METHODS OF PREPARING AND PRESERVING SUBJECTS OF ANATOMY, PATHOLOGY, AND NATURAL HISTORY, PREVIOUS TO THE PROCESS OF GANNAL.
Among the investigations belonging to the domain of medicine, normal anatomy and pathological anatomy occupy the first rank; they constitute the necessary basis of exact study: all men of genius have experienced this.
This conviction has been the source of the persevering efforts of numerous distinguished savans, who reasonably supposed that they would merit the esteem and gratitude of their species, if they could succeed in composing collections of engravings, or artificial models, representing the form, colour, &c., of each of the organs, or if they could discover methods of preparation capable of preserving the organs themselves with all the physical properties which they possessed at the moment of death.
It is not necessary to enter into discussions upon the high importance of these different kinds of investigations; for every one comprehends it, and the gravest authorities have pronounced upon this matter. Who does not know the vast importance which our illustrious Cuvier attributed in the progress of the natural sciences, to him who first conceived the idea of preserving objects in alcohol? It is perceptible, indeed, at the first glance, that the most beautiful and valuable of libraries for the physician and naturalist would be a collection of artificial subjects; or still better, of all the organs of the bodies of animals, and of man, skilfully prepared and preserved, without any alteration of the properties which it is important to know.
It must be admitted that a collection in which all the organs would be disposed in series, where they would be seen passing by their successive degrees of increment and decrement, offering their differences, individual and sexual, their points of contact and separation in the various classes of the animal kingdom, their anomalies, their pathological affections, their intimate structure, &c., it must be admitted I say, that such a collection would be an inexhaustible source of knowledge; it would acquire additional value by the addition of a series of pieces representing the detailed anatomy of each of the parts involved in surgical operations.
But this library, so eloquent and instructive, does it exist at the present time? Do we possess the means of forming such? The examination of the various processes, ought to furnish us with an answer to this question; it will besides enable our readers to estimate for themselves the part that our method may enjoy in the accomplishment of this object.
And first, in admitting the utility of engravings of models in wax, and in artificial carton,[L] in white wood, or in other compositions kept secret by their authors, we feel that whatever may be the accuracy of these different representations, they never can afford but an incomplete idea of the thing represented. 1st. Plates and engravings, so advantageous for reference, to recall the study made upon the corpse, have lost their importance in proportion as the means of obtaining dead bodies have become more easy: they are calculated to render great service and contribute to the progress of science in the fine anatomical works of Meckel, Lauth, Haller, Zinn, Hunter, Cruikshank, Cowper, Vic-d, Azyr, and of numerous other learned authors; at the present day, even, they are justly esteemed in the great works of MM. Cloquet, Bourgerie, &c. (The plates of the work of M. Bourgerie, are executed with remarkable care, and will form an epoch in the history of anatomical works.) But they occupy a secondary place, only to aid the memory; for of whatever good they may be, they must always have many inconveniences: 1. They fatigue attention, because it is necessary so often to multiply the figures, when it is requisite to examine an object under all its aspects where it is of importance to perceive it; 2. The organs are rarely seen of their natural dimensions; 3. Whatever may be the exactitude of the drawing, it is difficult to form a just idea of the relief and dimension of the organs; 4. The relations which they indicate are always incomplete; it is impossible thus to represent all the organs in their position, and in their natural relations.
2d. Models in wax, nearer to nature than plates, reproduces objects with admirable truth for the eye, but for the eye only. They were recently estimated of such importance, that courses on modelling were introduced into the schools in many cities of France; nevertheless, it cannot be concealed that pieces thus prepared leave much to be desired: 1. The relations of the organs which they indicate are very limited: 2. It is necessary then to multiply them to infinity, if it be desirable to represent under various points of view, the different points of the human body, which is indispensable, in order to comprehend their relations and connections: 3. And still the mind comprehends with difficulty the totality of objects viewed in a great number of pieces: 4. They cannot be handled and displaced as is requisite for study, without injury to them.
3d. Artificial pieces, which possess many of the inconveniences of wax models, are more proper to give a knowledge of the parts, which enter into the structure of man; nevertheless, if they be white wood, like the subjects of Fontana, or in Carton, like those of Ameline, or of M. Azoux,[8] they leave much to be learned of the properties which are requisite to an accurate and complete knowledge of the parts. Finally, these three means of communicating knowledge possess their degree of utility, but they can never support a comparison with the proper matter of the organs; they may serve to complete a museum, but never to form one; so we content ourselves to mention them here, in order to assign them a rank.
Anatomical pieces which place before the eyes the organs, themselves, are then the elements, “par excellence,” for the formation of collections, which are to serve as studies of normal anatomy, of pathological anatomy, and of natural history, but, the preparation and preservation of these pieces is a new science; we ought not to be astonished at it, notwithstanding the advanced state of our anatomical knowledge, if we reflect on the difficulties of all kinds, which prejudice excited in our predecessors. It is stated, it is true, that Ruysch, had discovered the means of preserving the dead body, with all the appearance of life, without drying, with florid complexion, and supple limbs. But, is this really the fact? and have we not good reasons to doubt such assertions, since no collection of anatomical pieces, prepared by this process, has descended to us, and no explanation has confirmed our knowledge of them?
We may then conclude, that the means of preparing and preserving, does not date much earlier than the commencement of the present century. None of them, however, has had for object the preservation of the entire subject: that which offers us the most numerous parts united in the same preparation has only a reference to anatomy, properly so called; it is the process of M. Swan, of England, given by him as a new method of making dried anatomical preparations, preserving to them the appearance and the advantages of fresh preparations, without possessing the inconveniences of them; this process is, as we shall see, only an application of the discovery of Chaussier, on the preservative properties of the deuto-chloride of mercury. We give it here, before passing in review the methods of preparation practised for each organ or each tissue.
“In order to describe the manner of making these preparations, I shall only take the arm by way of example.
“The member should be selected as clear from fat as possible. A solution of two ounces of oxymuriate of mercury, in half a pint of rectified spirits of wine, must be injected into the arteries, and the day after make another injection with the same quantity of white spirit varnish, to which must be added one-fifth part of turpentine varnish, and a small quantity of vermillion. The limb should next be placed in hot water, and remain there until it is sufficiently heated for a coarse injection into the arteries, and even the veins if necessary. If the veins are to be injected they had better be emptied of blood, with water, before forcing into the arteries the solution of oxymuriate of mercury, because there returns always by the veins some portion of this injection which coagulate the contained blood, and hinders the coarse injection from passing into the smaller branches.
“After the limb has been injected it may be dissected. Every time the work is left, it is better that the parts uncovered, should be enveloped in a linen cloth wet with water; and when the dissection is recommenced a great advantage will be remarked, which is that the parts injected with the solution of the sublimate will suffer very little alteration in several days, and are found in the same state in which they were left, whilst, by the common method, in one or two days, all is so changed that there is little profit in seeing what has been done, and if the dissection is long, they will scarcely be recognised when finished.
“Another advantage is that it may be dissected any where, since the preparation is without odour.
“When all the parts are uncovered, and all the fat and cellular tissue has been removed, the member thus prepared must be put into a solution of two ounces of oxymuriate of mercury, to one pint of rectified spirits of wine, and let remain entirely covered with this for at least fifteen days, for it cannot remain too long. A box of oak, painted white and varnished is the best recipient for the limb, whilst in solution; the cover must fit closely, in order to prevent the evaporation of the spirits of wine.
“The member must be withdrawn every two or three days, and any remaining cellular tissue is to be removed, and when returned to the tub the part which previously touched the bottom must be placed uppermost. The best thing upon which to place the preparation, when withdrawn from the solution, is a butcher’s tray, after having been well oiled; without this precaution the tray imbibes moisture, from which results a great loss of the solution. When the limb has remained long enough in the solution, it is to be taken out, to be painted and varnished.
“Before proceeding to these operations, the member kept in a state of extension, is suspended and dried, then endued with white varnish. On the same day the nerves, the tendons, and tendinous expansions, ought also to be varnished; which must be repeated once a day, for three consecutive days. The fifth day, the tendons, ought to be covered with a layer of yellow varnish, and white paint mixed in equal parts; this operation is to be repeated the seventh, eighth, and ninth day. The nerves, must also be endued, as often as necessary, with a mixture of equal parts of white paint, and white varnish.
“As soon as the muscles have become stiff, they may be painted, taking care that the nerves and tendons, are not touched by the paint. Nearly a month after the limb has been withdrawn from the solution, those of the nerves and tendons that are not sufficiently coloured should be repainted and varnished, as often as may be judged necessary. But always allowing a day’s interval between each application of paint and varnish.
“These operations being finished, wash lightly the tendons and nerves with boiled flax seed oil; this layer being dry, give a second over the whole limb; finally, several layers of copal varnish will terminate the operation. The first layer of copal varnish to be applied to the arteries with a slight addition of vermillion, and of Prussian blue, for the veins.
“In order to preserve the liver, it is necessary first to inject the vena porta and excretory ducts with white varnish, to which has been joined one-fifth of turpentine varnish, and some coloring matter, such as red lead. Then make the coarse injection, after which the liver is to be put into the solution for a least fifteen days; it is not necessary to heat it before injecting. The ligaments are to be prepared in the same manner as the tendons.
“We give below the paints, and varnishes, employed in the preceding preparations:
1.—White Varnish.
| ℞. | Canada balsam, spirits of turpentine, a.a. | 3 ℥. |
| Mastic Varnish. | 2 ℥. |
Put the whole in a bottle, and agitate until it is perfectly mixed.
2.—Mastic Varnish.
| ℞. | Powdered mastic. | 4 ℥. |
Dissolve in a pint of spirits of turpentine.
Agitate daily, until the mastic is dissolved.
3.—Yellow Varnish.
Infuse one ounce of gum-gutta in powder in eight ounces of spirits of turpentine for fifteen days; then, with equal parts of this clear drawn liquor, Canada balsam, and mastic varnish, form the yellow varnish.
4.—White Paint.
Three ounces of white lead, and an ounce of spirits of turpentine serves to form it.
5.—Paint for the muscles.
It is made of Lac, Prussian blue, and white varnish, to which is added one quart of turpentine varnish.
6.—Red Injection.
| ℞. | Wax, | 4 ℥. |
| Copal varnish, | 1/2 ℥. | |
| Red lead, | 1/2 ℥. | |
| Vermillion, | 1 ʒ. |
Melt together.
7.—Green injection.
| ℞. | Wax, | 4 ℥. |
| Blue dross, | 1/2 ℥. | |
| Copal varnish, | 1/2 ℥. |
8.—Blue injection.
To form this it is only necessary to add to the green injection, half a drachm of powdered Prussian blue.”
The advantages of such preparations do not answer, in any degree, to the promises of the title; the artificial preparations of M. Azoux are much more preferable, since his cartons represent the form which the anatomical pieces of Swan have lost by desiccation.
Section 1.—Generalities of the operations which precede preservation.
Desiccation and immersion in liquids are the only means of preservation.
The choice of subjects which are to serve for these preparations, says M. le Docteur Patissier, is not a matter of indifference. Young subjects, and lean women, are preferable for the nerves and bloodvessels; adults, and thin and dry old men, for the preparation of bones which it is intended to articulate, and which it is desirable to obtain in their greatest degree of development; individuals of an athletic constitution for muscular preparations.
The most favourable time for the preparation and preservation of anatomical subjects, is generally during a cold and dry winter, or the ardent heat of summer; the more rapid is the evaporation of the humidity of animal matters, the more sure is their preservation.
The method of preservation ought to be preceded by some other operations, such as dissection, maceration, injection, ablution, corrosions, ligature of vessels, separation and distention of parts.
a. Dissection.—It consists in stripping the part which it is intended to preserve, of the tissues and organs which are foreign to it: if the object be the preparation of muscles, for example, these organs are left alone with their insertions in the bones, or rather, the vessels, previously injected, preserve their relations with the muscles and the bones. Nevertheless, in the dissection of the hard parts, whether it is proposed to follow the branches of the vessels and nerves which penetrate, or are distributed in their substance, or whether it is desired to develop and render their organization more apparent; it is less convenient to have recourse to instruments than to chemical re-agents, which bring into view the parts which it is desirable to study. When the object is the preparation of a bone only, the operation consists of two parts, excarnation, and etiolation, the details of which will be presented in the article upon bony tissues.
b. Macerations and corrosions.—These operations are frequently brought into use by the naturalist: water, acids, alkalies, volatile oils, &c., serve to produce varied effects in the preparation of the different tissues. The maceration of different portions of the skeleton is produced by water. The employment of other liquids has for object, in attacking several parts which they dissolve, to expose others which it is desirable should be left bare.
Thus, in order to absorb the grease which exudes from the skeletons of certain fish, or of bones, the maceration of which has not been perfected, it is useful to steep the piece in a marly alluminous paste, which must be alternatively put to dry and soften in the sun, in order that the clay may absorb the fetid oils with which the bones are impregnated.
In order to dissolve the grease with which certain parts are covered some time after their preparation, as happens to some natural skeletons, it is often necessary to steep the piece in an alkaline liquor, or rather, to allow it to macerate for some weeks in a very penetrating volatile oil. It is only by the aid of such processes that we are able to follow encephalic nerves in many of the cetacea, although these parts present in these animals extremely singular dispositions.
It is with the same view that should be macerated either in water elevated to a certain degree of temperature, or in acid liquors, the hard tissues, in the interior of which it is proposed to denude certain parts. Thus the nerves and vessels of the roots of the nails, the horns, the skin, cannot be well exposed but by this process. The canals, which traverse certain bones, cannot, as we have already shown, be easily followed, unless the piece has remained for a longer or shorter time in an acid liquor.
Macerations in alkaline and etherial liquors are still of great assistance, as the researches so happily conceived and executed by Bichat have proved.
Finally, corrosions are indispensable to the removal of the parenchyma from injected preparations, when it is intended only to preserve the interior network of vessels.
The following are the attentions which this operation exacts: The injected part is consigned to a vessel of pure water for two or three days, which is occasionally to be renewed, in order the better to disgorge the vessels of any blood they may contain. It is afterwards to be solidly fixed on a piece of wax at the bottom of a porcelain vase, pierced with holes near the base, through which the liquor used to wash them may flow off without deranging the vessels. This corrosive liquor is the muriatic acid, or spirit of salt; the aquafortis of engravers, or nitric acid, may be used for the same purpose.
The first time, the preparation is to remain two or three hours in this acid, which is then drawn off and replaced by the same quantity of water, which is allowed to flow on it in small streams. This water is left for four or five days, according to the season, until the water begins to be covered with a scum, and the preparation begins to be cottony at its surface; the liquor is poured off a second time, and the pot or vase is placed beneath the cock of a fountain, from which escapes a delicate stream of water, which will carry off slowly and without shocks, any detached parts; when it is perceived that the washing carries off no more animal matter, the acid is poured into the pot, of which the opening is to be reclosed with a stopper of glass or porcelain, warmed and endued with wax. This operation is to be repeated every four or eight days, until the tunics of the vessels are altogether denuded, and the injected matter is seen throughout.[9]
c. Injections.—These are evacuative, repletive, antiseptic, or preservative. The first have for object, as their name indicates, to disembarrass the vessels or hollow organs, of the matters and fluids which they contain; they consist of water, of acids very much reduced, of diluted alcohol, &c. Thus it is serviceable to inject water or alcohol into the bloodvessels to prepare them for the reception of the repletive and preserving injections. The second are either definite or temporary.
The substances employed in these injections are vehicles for colouring matter. The nature of the vehicles determines that of the colours, which ought to be as far as possible, analogous to those of the humors, which the vessels contained during life.
As vehicles, those fluids which always retain their fluidity are rarely employed, for parts thus injected cannot be dissected, and they are, besides, apt to allow the colouring matters which they contain in suspension, to be deposited.
Liquids saturated with glue or gelatine, made use of in ordinary injections, have the inconvenience of not being equally solidifiable at different degrees of temperature, or harden too rapidly by cooling; they are made with the glue of commerce, either simple, or mixed with gummy or saccharine matter; that commonly used, is called Flanders glue, although it is manufactured in Paris, and that called mouth glue, which only differs from the other in containing a little gum or sugar. That which succeeds best, because it melts with the heat of the hand, and which nevertheless coagulates at a temperature of twenty-five or twenty-six degrees of Reaumer’s thermometer, which is one of the highest points to which our atmosphere attains, is made of the membranes of fishes, or icthyocolla. An ounce is to be melted in a sand-bath, in double its weight of water, and mixed afterwards with two ounces of alcohol, previously warmed. In these sorts of gelatinous injections, there is much choice in the colouring matters. All those that are ground like gum, and which are used in miniature painting, and in painting “a la gouache,”[M] may be employed; they remain very well suspended.
The sticks of carmine of Delafosse, and the carmine lacks of Hubert, may then be used with advantage for the arteries; for the veins, Prussian blue, ground in vinegar, and the white of zinc of Antheaume, or that of oyster shells well porphyrized, for the colour of metallic oxide is subject to change in animal matter; they are also subject to the inconvenience of becoming precipitated by repose before the vehicle cools, and thus obstruct the smaller vessels.
Liquors which can be made solid by the effect of certain re-actives, offer, on this account, some advantage. It is thus, that it is serviceable to soak for a day or two in a solution of nut-galls or of tannin, those parts injected with gelatine, when it is intended to preserve them dry. In partial injections of lymphatic vessels, and particularly of the chyliferous, cow’s or goat’s milk, may be made use of. When, after having tied the thoracic duct, injections of milk have been made into all the vessels in which can be introduced the beak of a glass syringe, or of the syringe used for injecting the lacrymal ducts, pour on the surface of the injected parts strong vinegar, or a diluted acid, which will coagulate the milk, so that the chyliferous vessels will be found filled with a solid, white, and flexible.[10]
The most common, the most solid, and the most convenient injections, are made of fatty and resinous matter. Volatile oils, balsams, resins dissolved in alcohol, fats, wax, and the most ordinary fixed oils, are principally used. These different substances are combined, and the compositions of them are varied according to the nature of the injections, which it is desirable to prepare, and above all, according to the manner which it is proposed to preserve them.
The nature and the preparation of the colouring matters, ought also to vary according to the kind of fatty medium which is used.
The volatile oils being nearly equally penetrating, turpentine is generally chosen, because it is cheaper. Nevertheless, for small objects, the citron, or that of a species of lavender (aspie of the shops) is preferred, on account of their odour, which are besides not very expensive. When it is intended to inject only with one of these oils, which makes a liquid matter extremely penetrating, after having dissolved a colouring matter previously ground in a fixed oil, the mixture is slightly heated. This liquor is generally employed to render perceptible the small vessels of membranes, which are not to be dissected, but well preserved in their integrity. If it is intended to inject the large trunk which supplies these membranes towards the end of the operation, it is necessary to inject a little essence of varnish, charged with much resin, and before drying the piece, let it soak a day or two in an aqueous solution of the deuto-chloride of mercury, according to the process of Chaussier.
The matters with which the volatile oils are to be coloured, should be previously ground with the greatest care. It is easy to procure those which are prepared with nut oil, and which are sold in little bladders to be employed upon palettes.
Colours, thus prepared and intimately amalgamated with fixed oils, remain much better suspended; the heaviest oxides, even those of lead and mercury, are not then subject to become deposited.
Resins, dissolved in spirits of wine, are also sold by the pint, all prepared, under the name of varnish, and in general are not costly. Those which the anatomist can turn from the ordinary arts to his own profits, are employed principally in pieces which it is intended to preserve dry. Perfect success attends the varnish, named in the shops fat, wood-red, à la copale, and with some others which remain a long time flexible.
These fluids are difficult to colour; it is necessary, for the first, to grind the colouring matter with essence, and for the others with alcohol; and to incorporate them afterwards with varnish after having slightly heated them. The carmined lakes, thus suspended in fat varnish, produce absolutely the effect of arterial blood; this colour preserves very well, and with such like injections it is unnecessary to colour the surface of the arteries.
The mixture of mutton fat or of suet, of white or yellow wax, of the fixed oils of olives, nuts, or flax seed, are the ordinary matters of injections, even for those destined for corrosions. The different degrees of solidity or softness are determined by the calculated proportions of wax and oil, and by the amalgam of resinous and colouring matters.
In general, in this sort of injections it is advantageous to introduce beforehand, a small quantity of volatile oil mixed with the fatty matter which is to serve for filling the vessels; by this preliminary process a liquid more fluid, more penetrating, higher coloured, and susceptible of cooling more slowly, is driven before into the smaller ramifications.
I could here transcribe several receipts proper to indicate the proportion of fatty matters among themselves; but the season during which the pieces are made, the nature of the ingredients employed on them, will occasion the proportional quantities to vary, so that a sketch only can be given for obtaining a matter which may be made more solid or more fluid after having tried it by cooling some drops separately. Nevertheless, here is one of those receipts:
| ℞. | Of suet, | 5 | parts. |
| Burgundy pitch, | 2 | " | |
| Oil of olives, or of nuts, | 2 | " | |
| Of fluid turpentine and colouring matter, dissolved in volatile oil, | 1 | " |
This latter part should not be mixed until the liquor is well melted and ready to be put into the syringe, as the heat will volatilize the volatile oils, which will become disengaged in the form of gas, and cause the mass to occupy a very great volume.
As a matter of injection, the dissolved gum elastic or caoutchouc may be employed; it becomes gelatinized in losing a portion of its menstruum by desiccation. After leaving this matter in a moist place, and having well washed it, in order to clean it of the clayey matter which generally impregnates it, it may be dissolved in volatile oils by heating it in a sand bath, with a moderate fire in a matrass with a long neck; adding by degrees, a sufficient quantity of oil to render the mass very fluid, incorporating with it the colouring matters which have been previously ground in an essential oil. The gum elastic may also be dissolved in ether, but this process is too expensive; and as a matter for injecting this liquor is not preferable to the other. The elastic injections are only advantageous in the preparation of parts which are not to be exposed to cutting instruments, and to which it is desirable to preserve a certain degree of suppleness, as in the injection of the cotyledons, or the placenta of women. This liquor, it must be confessed, has the great inconvenience of retaining its odour a long time, assuming its solid form with difficulty, and of rendering the preparations pitchy, and rebellious to varnish, and becoming loaded with dust.
There are certain organs which may be injected with solid matters, in order to obtain, in relief, resisting, but coarse, the forms of interior cavities. Such is the injection with the matter which forms the stucco paste, or of fine plaster diluted with gelatinous water, which gives to this salt a greater solidity when it takes its consistency. This gross matter is employed with advantage to render more solid the membranes of certain cavities, in the thickness of which it is desired to search for the nerves. Pure wax does not present the same advantage, because it exacts more heat, and contracts more by cooling, although it is more applicable in case it is proposed to corrode with acids all the fleshy or osseous parts, in order to become acquainted with the real form of their interior capacity: in fine, the fusible metallic mixture of Darcet is employed under different circumstances, but it is not more useful.[11]
Preservative injections, which may also be applied to vessels and to hollow organs, are composed of materials to which have been attributed preservative properties to the tissues: such are the solutions of mercurial salts, arsenical, ferruginous, &c., and different aromatic and spirituous liquors.
d. Ablutions.—These vary according to the end proposed: acids; these serve to give whiteness to some tissues and resistance to others: alkaline; these clean the preparations, divesting them of the mucilage and grease which they contain. In one word, the action of aqueous liquids, of oily, alkaline, saline, acid, alcoholic, is necessary before, as well as after dissection to preserve the preparations.
When these preparations are left a longer or shorter time in water, they are subjected to what is called a degorgement; the bath ought to be renewed until it will no longer receive any colouring matter.
The removal of grease is included under dissection, maceration, and ablution.
e. Ligature of the vessels.—This is made with a flat silk, or silk very slightly twisted, during the dissection, or immediately after, on the extremity of the vessel which contains the injection; it is necessary in order to prevent the escape of the injected matter.
f. Separation and distention of parts.—These offer the whole surface of the prepared pieces to those agents of preservation which ought to be applied to them; they sustain them, and preserve them from being deformed. Besides, it is well known, that the means of separation and distension ought to vary according to the form of the organs; atmospheric air suffices for hollow and thin organs, the stomach, the intestines, the bladder, &c. Under other circumstances, wool, hair cotton, plaster, &c., serve better.
Sect. 2.—Means of Preservation.
The means of preservation may be arranged under two principal heads, as we have said, according as the anatomist intends to expose his preparations to the open air, or to preserve them from insects and render them more transparent by the aid of certain liquors, in which it is intended to keep them continually.
Preservation by desiccation.—When applied to soft parts is only applicable to anatomy, properly so called, and to natural history; it cannot be employed for specimens of pathological anatomy.
Desiccation is preceded by a more or less prolonged immersion, according to the thickness of the organs in acid or saline solutions, &c.; that which presents the greatest advantage for the nerves, according to Dumèril, is diluted nitric acid. The salts commonly employed present some inconveniences. Corrosive sublimate hardens too much, and causes the parts to contract on each other; the triple sulphate of alumine, (alum,) often chrystalizes in drying, which produces in the interior of the piece, which ought to be pellucid, saline vegetations, which not only elevate the organic lamina, often rendering the surface tuberculous, but further deprive the part of the transparency necessary to see the texture of it; the muriate of soda, (white kitchen salt,) attracts the humidity of the air, and causes the varnish to scale off, which can have no hold upon the preparation. Diluted nitric acid, with which the parts are washed, does not expose them to these inconveniences: the preparation preserves, it is true, a certain degree of suppleness; it tarnishes a little, but is never humid.
The numerous means used for disposing the preparations to desiccation, may be reported under four series:
Alcohol, where expense is no object, is preferable to all the others; its affinity for water gives it the property of absorbing humidity from anatomical pieces.
The deuto-chloride of mercury, the proto-nitrate of the same base, the solutions of acetate of lead, and of the proto-nitrate, merit the preference among metallic substances.
Marine salt and alum are nearly those alone among the earthy salts which have been employed for this object. M. Breschet advises that, according to the method followed by the tanners, the piece be permitted to remain for several days in powdered sea salt, and to immerge it afterwards in a strong solution of alum for fifteen days, when it is to be withdrawn and dried.
In fine, tanning is still a preparatory method for desiccation.
Desiccation.—Anatomical pieces may, says M. Doct. Patissier, be dried in the open air, in a stove, in a vacuum, and by employing substances very avaricious of water, and in a bath of sand, or of absorbing powders; but desiccation by means of an oven is the best process: the heat of the oven must be neither too weak nor too strong; the most convenient temperature is that of 45° to 55° of centigrade.
When the parts have been dried by one of the processes just mentioned, if they be abandoned to themselves, they would become injured in a little time by humidity and insects. There remains, then, some care to be taken before depositing them in a cabinet; they should be washed in a liquid containing a preparation of arsenic, or of sublimate, or rather by applying to them a varnish containing one or both of these substances. We shall not reconsider here the compositions of varnishes, having already given several formulæ for them when speaking of Swan’s method, and we shall have occasion to refer to them again when passing in review the different methods of preparing objects of natural history.
Preservation in liquids.—Anatomical parts are also preserved, and more advantageously, in liquids. We shall now consider the acids, or acidulated waters, alkalies, salts, oils, spirituous or alcoholic liquors; expose their advantages under certain circumstances, their inconveniences under others.
When acids are employed for preserving anatomical parts in their natural state of suppleness, caution must be used to dilute them, with a sufficient quantity of water, so that they may not corrode or harden the parts. In general, it is advantageous to allow them to remain for the first few days, in a very weak acid, and not place them in the prepared liquor, until they have ceased to make any deposit. The objections against muriatic acid are, that it renders the surface of the parts gelatinous, gluey, and transparent; of nitric acid, to tarnish and contract them; of sulphuric acid, to bleach them. All these acids decompose the parts when they are not sufficiently diluted with water; they allow the liquor to putrefy or to freeze, and break the vessel when they are too weak. The proportions are indicated by experience, and depend upon the nature of the part which it is intended to preserve. It is those parts in particular which are loaded with fat, that are best preserved in acid liquors.
In general, little use is made of liquors which hold alkalies in solution: the carbonates of commerce are preferable; and these are used with advantage, when it is necessary to keep for several days, before dissection, animal parts in which corruption has already commenced.
Those salts derived from the combination of acids and earths, the alkalies or metals, may be employed like the acids diluted with water. They are not subject to the same objections. The nitrate of potash, the muriate of ammonia, those of lime, or of soda, are very proper for preserving pieces of myology; they appear even to reclaim the red colour of the muscles, when these solutions are strongly saturated; but, then, they are liable, some of them, to liquify, others, to effervesce or to chrystalize upon the sides of the jars, and even on the surface of the parts themselves, which is a very great inconvenience when it is wished to expose the parts to view.
The solution of the triple sulphate of alumine, (alum of commerce) is employed with the same advantages; it must be confessed, however, that they are more proper to preserve membranous parts which have been previously allowed to macerate a long time. In general, this liquor discolours the parts, and deposits at length on the sides of the jar and the surface of the piece which it bleaches, the white earthy matter with which it is charged; this is a great objection, and exacts great care when the atmosphere freezes suddenly.
Chaussier has latterly proposed the solution of the deuto-chloride of mercury, in distilled water. This liquor is very useful, but it bleaches the surface of the parts, particularly the muscles; it hardens, and attacks the instruments when new researches are attempted, upon parts already prepared. This discovery, however, is very valuable to obtain the mummification of certain parts, which it is intended to preserve in the open air. In order to obtain a solution always equally saturated, Chaussier,[12] has proposed to keep at the bottom of the liquor two or three knots of fine linen enclosing a certain quantity of this metallic salt, in order that the saturation may always be complete.
In general, we repeat, these preservative liquors are attended with the great inconvenience of leaving suspended, after frosts, the albuminous matters which the cooling has caused to precipitate; so that the fluid of the vessel which contains the preparation becomes clouded, and no longer permits the object so be clearly seen. Besides, the liquor freezes, and breaks the jar, when the temperature is very low.
The volatile oils, from whatever vegetable they may have been extracted, are very proper for the preservation of anatomical objects; they lose at length, it is true, their transparency; they thicken, precipitate to the bottom of the vessel, the animal fluids which exude from the object, which exposes them to corruption. But all these changes are sensible to the eye, and the fault is easily repaired when perceived in time to renew the liquor, which may be afterwards re-distilled.
It is never useful to employ these liquids for the preservation of objects loaded with fat, for they dissolve these at length and penetrate them entirely, changing their form and colour.
Volatile oils, and particularly turpentine, which is the best, are employed to preserve with the greatest success certain injections, the vehicles of which would be dissolved in alcohol, and all the parts whose vessels have been injected with coloured gelatine; finally, these oils are used in all cases where it is desirable to preserve the transparency of certain membranes, which have been previously dried.
Alcoholic liquors are most generally used for the preservation of animal substances, if they are more costly, they are liable to fewer objections. Brandy, rum, tafea, are coloured by a resinous substance, which clouds their transparency, and which is liable to be deposited. The alcohol of cherries, of grain, of cider, or of wine, is preferred at present, which can be procured well rectified and transparent, and which may be afterwards weakened with distilled water, so as to obtain alcohol very limpid, marking from 22° to 30° of Baumè’s areometer.
Some years since, alcohol was still employed, in which was dissolved certain transparent resins; such as camphor, but it has since been ascertained, that animal substances which have remained in this liquor, contract such a disagreeable and nauseous odour, that it becomes very painful to keep them long uncovered for examination, consequently, pure alcohol is preferred.
Nevertheless, when it is desirable to preserve the preparations of the nerves, it is better to put a few drops of muriatic acid into the jar along with the spirits of wine: this mixture bleaches and renders more visible the nervous fibres, on which the acid appears to act more specially. The yellow tinge, which the parts sometimes assume in the end, may sometimes be removed by pouring a small quantity of muriatic acid into the jar which contains them: this precaution occasionally gives a new aspect to the parts.
We have chosen this passage of M. Dumèril’s pamphlet, because it gives with sufficient accuracy all the liquids employed by preparors, and because it indicates a part of the inconveniences which we have experienced from them.
We shall see to what extent the more recent additions made to sublimated alcohol, of hydrochlorate of soda, (chloride of sodium,) of the hydrochlorate of ammonia, of the muriate and nitrate of alumine, can contribute to the wants of the collector of pathological anatomy.
Before entering into this critical examination, it remains for us to describe the processes employed by naturalists for preserving the different species of animals. The excellent manual of M. Boitard, so useful to preparors, will furnish us with this information.
Means of preparing and preserving practised by naturalists.—The soap of Bècoeur enjoys with naturalists a great reputation as a preservative. It is this preservative, then, that we should recommend as the most approved by experience: the following is the receipt:
| ℞. | Arsenic pulverized, | 2 ℔. |
| Salt of tartar, | 12 ℥. | |
| Camphor, | 5 ℥. | |
| White soap, | 2 ℔. | |
| Powdered lime, | 8 ℥. |
In the original, four ounces of lime is recommended, and we have given this dose in our first edition; but it has since been found by doubling it, the preservative is less pasty, and less difficult to use, more abundant and equally good.
M. Simon thus composes the preservative, but he adds to it a certain quantity of corrosive sublimate, and of camphor dissolved in spirits of wine. The camphor, thus incorporated with the preservative, does not volatilize so easily as when used in powder.
When used, a sufficient quantity is placed in a small vessel, and, with the aid of a hair pencil, it is moistened with water and spread upon the piece to be preserved.
Some naturalists, fearful of the danger of the daily use of arsenic, have endeavoured to replace this preservative by another composition, but have never succeeded in obtaining results equally advantageous; but, nevertheless, in order to render this work as complete as possible, and to facilitate new researches, we thought that we should at least, indicate here, the different processes which have by turns been imagined.
In my cabinet of natural history, I have indicated, under the name of soapy pomatum, the following composition:
| ℞. | White soap, | 1 ℔. |
| Potash, | 1/2 ℔. | |
| Powdered alum, | 4 ℥. | |
| Common water, | 2 ℔. | |
| Oil of petroleum, | 4 ℥. | |
| Camphor, | 4 ℥. |
M. Mouton de Fontenille proposes a tanning liquor thus composed:
| ℞. | Quinquina, | 1 ℥. |
| Grenada bark, | 1 ℥. | |
| Oak bark, | 1 ℥. | |
| Gentian root, | 1 ℥. | |
| Absynthium, | 1 ℥. | |
| Tobacco, | 1 ℥. | |
| Powdered alum, | 1 ℥. | |
| Common water, | 2 ℔. |
Boil the whole, except the alum, which is not to be added to the liquor until withdrawn from the fire; it is to be put into a well corked vial for use.
M. Mouton thus uses his liquor: when an animal is skinned, and the skin divested of grease as well as possible, the internal surface is to be moistened with the tanning liquor until it is perfectly impregnated; if it be a dry skin, it is to be moistened in the same manner until it is softened.
An author has recommended, under the name of antiseptic powder, the following composition:
| ℞. | Arsenic, | 1 ℔. |
| Calcined alum, | 1 1/2 ℔. | |
| Purified sea salt, | 1/2 ℔. |
The whole to be reduced to a fine powder and well mixed.
We advise that powdered arsenic never be used, because, by volatilizing, it might penetrate the lungs and cause mortal ravages.[N]
The preparor Nicholas recommends, in certain cases, a composition which ought to be here mentioned, not to advise the use of it, on the contrary, to advise the rejection of it; for far from driving off the insects, it attracts them; he calls it gummy paste.
| ℞. | Colocynth, | 2 ℥. |
| Gum Arabic, | 4 ℥. | |
| Amidon, | 6 ℥. | |
| Cotton, hashed fine, | 1 ℥. |
Other preparors, without passing any thing over the skin, confine themselves to the use of the following powder:
| ℞. | Calcined alum, | 3 ℥. |
| Flour of sulphur, | 1 ℥. | |
| Black pepper, | 1/2 ℥. | |
| Powdered tobacco, | 1/2 ℥. | |
| Powdered sabine, | 1/2 ℥. | |
| Powdered camphor, | 3 ʒ. |
The whole to be finely powdered and well mixed.
Some amateurs content themselves in passing over the internal surface of the skin they wish to preserve, a good layer of melted suet mixed with a small quantity of corrosive sublimate; it appears that they have obtained some advantageous results, which authorises further experiments; it has been remarked, that suet is never attacked by insects; perhaps, if it were combined with some mineral matter less dangerous than the sublimate, results as satisfactory as those from the arsenical soap of Bècoeur might be obtained.
Such are the preservatives which have been employed in France, but which do not possess, to any extent, the efficacy of the arsenical soap of Bècoeur. It appears that the Germans employ others to which they attribute the same qualities, which appears to us very doubtful in all cases: they may be mentioned here.
Naumann, in the first place, gives a method which appears to us vicious, although he invokes in its favour his own experience. After having said that the best method of preserving is to close hermetically, stuffed animals in boxes, he adds: “I do no more for skins which are to travel in boxes, than powder them with the following composition:
“Of lime decomposed in the air, and finely sifted, two parts; of saxony tobacco, also sifted, one part.”
Hoffman approves of, and recommends the following powder:
| ℞. | Sal ammoniac, | 1 ℥. |
| Calcined alum, | 1/2 ℥. | |
| Saxony tobacco, | 3 ℥. | |
| Aloes, | 1 ʒ. |
The librarian of Jena, M. Theodore Thon, proposes the following powder, as better for preserving animals in the open air.
| Cobalt, | 1 ℥. | |
| Alum, | 2 ℥. |
To be powdered and mixed. Before employing this powder, give a layer of essence of pine, (turpentine,) in order that it may adhere better to the interior of the skin. If the latter be very greasy, add an ounce and a half of lime decomposed in the air and sifted.
Among the preservatives which this naturalist has investigated, we find a very simple one, which he says, is very effectual for mammifera: the following is its composition:
| Cobalt in very fine powder, | 4 ℥. | |
| Alum, | 4 ℥. |
The same naturalist recommends another composition as very good, and which I think would be worth making a trial of for large animals, which would be very expensive done with arsenical soap. Very fat bitumen is to be melted, in a strong solution of soap-water, until the whole forms a sort of clear broth; the interior of the skin is to be endued with this mixture, which costs very little.
Preservatives in Liquors.
Liquors are employed in baths, in lotion, in friction, in injection, and finally, in permanent baths, in which certain objects are always to remain; we shall now treat of these four methods of preservation.
Of the Bath.
In many animals, and particularly in the mammifera, the skin has such a thickness, such a degree of intensity, that the arsenical soap can not penetrate it sufficiently in order to preserve it perfectly; it is then that the bath becomes an indispensable operation. In penetrating the skin which is left to macerate a longer or shorter time, the preservative molecules with which it is saturated enters all its pores, and preserves it for ever from the attacks of insects.
The following is the composition of the bath employed by the naturalists—preparors of Paris.
| ℞. | Common water, | 5 ℔. |
| Alum, | 1 ℔. | |
| Sea-salt, | 1/2 ℔. |
This mixture must be boiled until it is all entirely dissolved, and when the liquor has cooled, plunge the skins into it; those of the size of a hare, or thereabouts, need not remain longer than twenty-four hours; those of the larger animals must macerate a longer or shorter time, according to their thickness; from eight to fifteen days would not be too long for a buffalo or a zebra. At the museum of Natural History of Paris, they very rarely make use of this composition; they are satisfied to macerate the skins in spirits of wine, which they keep in hogsheads for that purpose. Without attempting to criticise this method, which may have its advantages, we think that they might, perhaps, in this particular, follow the English naturalists, and add, like them, a small quantity of corrosive sublimate dissolved in spirits of wine.
Nevertheless, as we ought to be impartial, we should mention here the dangers attendant on the use of this terrible mineral, so much boasted by Sir S. Smith, president of the Linnean Society of London. When there is occasion to mount a subject prepared with sublimate, whether it has been employed in powder or in solution, in arranging the animal there arises a dust, which penetrates the nostrils, and may cause serious accidents. Arsenic, though much less energetic, is not even free from this inconvenience. Thus it is only with much precaution that preparors should handle preparations in skins which they receive from foreign countries, the substances used in the preparation of which they are ignorant.
Let us now pass to the other preservatives in liquor, less generally employed, at the present time, although some of them may be very useful. The following is the tanning liquor which I have proposed in the Cabinet of Natural History:
| Tan, or oak bark, | 1 ℔. | |
| Powdered alum, | 4 ℥. | |
| Common water, | 20 ℔. |
An ancient author, the Abbe Manesse, composed his bath in the following manner:
| Alum, | 1 ℔. | |
| Sea-salt, | 2 ℥. | |
| Cream of tartar, | 1 ℥. | |
| Common water, | 4 ℔. |
Liquors employed externally as lotion.
When an animal has been mounted or prepared, and fears exist less the insect should attack it, this may be prevented by washing its feathers, its hairs, or its naked skin, with one of the liquors which we are about to indicate. Animals exposed to the open air have, above all, need of being thus treated, and yet, by an inconceivable negligence, many amateurs permit their collections to be devoured, for the want of employment of a means both simple and easy.
1. The essence of wild thyme, has been recently advantageously employed; in using it the feathers or hairs of an animal are to be raised every little distance by a long needle, and at their bases, that is to say, the skin, is to be touched by means of a hair pencil with a drop or two of the essence, and when this has been well imbibed, the hairs or feathers are to be replaced, their extremities, never being in contact with the liquor, cannot become tarnished.
2. Essence of turpentine has been recommended by almost all authors, and yet, when made use of it is perceived with astonishment that great inconveniences result; it never dries upon the feathers, which it greases and soils in spite of every precaution, the spots spreading and enlarging like oil; besides this, it forms a species of glue, which arrests and fixes the dust in such a manner that no subsequent effort can remove.
3. Liquor of Sir S. Smith.—This intelligent English naturalist, president of the Linnean Society of London, having turned his attention to the preservation of prepared objects, already classed in collections, has concluded that there cannot be a more efficacious means employed than the following liquor.
| ℞. | Corrosive sublimate, | 2 ʒ. |
| Camphor, | 2 ʒ. | |
| Spirits of wine, | 1 ℔. |
In large animals it is applied by means of a sponge, which is passed at different times over the whole exterior of the animal, until it is perfectly impregnated, and the liquor has penetrated to the skin. In small animals a hair pencil is used, and the operation is performed in the same manner. Whether the individual submitted to this practice be recently prepared, or whether it has long remained in a collection, it must be permitted to dry perfectly before placing it in a cabinet.
In France this dangerous composition is replaced by the preservative in very small quantities diluted with water.
4. The bitter spirituous liquor, recommended by other authors, is thus composed:
| ℞. | White soap, | 1 ℥. |
| Camphor, | 2 ℥. | |
| Colocynth, | 2 ℥. | |
| Spirits of wine, | 2 ℔. |
The whole is to be subjected to cold infusion for several days in a vessel hermetically sealed, frequently shaking the vessel during this interval, and allowed to strain through unglazed gray paper; when it is thought that the infusion is done, it must be put into bottles equally well corked, and used after the same manner as the preceding.
5. Varnish is employed only on the naked skin of reptiles and fishes, to which it restores a portion of its splendour; it must be absolutely colourless, and perfectly transparent. In order to obtain it thus, it must be prepared by dissolving fine and new turpentine in spirits of wine, which must themselves possess the qualities above mentioned. It is to be applied with a pencil of squirrel’s tail, or the tail of a martin, and the object is left exposed to the air, sheltered from the dust, if it be wished to hasten its desiccation.
Liquors employed in Injections.
Injections are more generally employed for the preparation of the eggs of birds, for which it is desirable to secure a long preservation; although by a very bad method, they have also been used for the desiccation of very small animals.
In order to decompose the flesh of a fœtus already formed in an egg, recourse is had to a strong solution of a fixed alkali, of soda, of tartar, or to ether.
Liquors, in which objects are preserved which do not admit of drying.
The qualities which a liquor ought to possess, in which objects of natural history are placed, are, independently of that of preserving from decomposition: 1. to be colourless, that they may not tarnish the contained objects; 2. not to attack by corrosion the proper colours of the object; 3. to be perfectly transparent, that the contained objects may be visible through the vase which encloses them; 4. the power to resist frost, in order that they may not break the jar which holds them.
1. Spirits of wine, of from fourteen to eighteen degrees of the areometer of Baume, appears to be the liquor which best fulfils all these conditions; the other alcohols, such as those from potato, from grain, from sugar, &c., have the same qualities; but a serious inconvenience is the high price of all of them, and this reason alone is an inducement to look for other compound liquors, capable of replacing them with more or less advantage.
2. Nicholas recommends the following composition:
| Very pure water, | 2 ℔. | |
| Alcohol, | 1 ℔. | |
| Sulphate of alumine, | 6 ℥. |
The English naturalist, George Graves, in a work published in London, seven years ago, indicates a liquor which has much analogy with the preceding:
| Alum, | 8 ℥. | |
| Common water, | 1 ℔. | |
| Alcohol, | 1/2 ℔. |
The following is the method of preparing this mixture: the alum is pulverised and put into a vessel capable of resisting heat; water being heated to ebullition is poured upon the alum; when cool, it is to be filtered through gray paper, and then mixed with alcohol. The same author recommends another liquor, thus composed, but of which the mixture is made cold.
| Common water, | 1 ℔. | |
| Alcohol, | 1 ℔. | |
| Alum, | 12 ℥. |
4. The Abbe Manesse, after various trials, more or less successful, has published the result of his experiments; he proposes as the best liquor, one composed as follows:
| Alum, | 1 ℔. | |
| Nitre, | 1 ℔. | |
| Sea salt, | 1 ℔. | |
| Common water, | 4 ℔. | |
| Alcohol, | 1 ℔. |
The water used should be distilled, so as to be freed of any foreign matter; the alum should be the most transparent that could be obtained, and the salt also should be purified before use. The liquor may be made cold, but it is always better to boil it, with the precaution not to add the spirits of wine until it has cooled.
All these liquors are inferior to spirits of wine, inasmuch as they are liable to freeze.
After having given this long list of the known means of preserving, and given in detail the representation of authors, it remains for us to judge of them, to determine their merit, and the degree of confidence that ought to be accorded to each, under the triple point of view of the preservation of objects of normal anatomy, of pathological anatomy, and of natural history.
1. Process of desiccation.—It can be of no utility for pathological anatomy, because it changes entirely the aspect and texture of parts, and in most cases it leaves no traces of the alterations which it is important to know. For normal anatomy, these preparations are, and always must be, from the simple fact of desiccation, a feeble resource, and really much inferior to the artificial subjects of M. Azoux; for this ingenious preparation, if it has many of the faults of dry anatomy, the objects are not so deformed as scarcely to be recognised.
Further, each of the preparations which tend to desiccation has its particular inconvenience: thus those of the deuto-chloride are numerous, as we have seen in the preceding chapter, and as have remarked in this the authors whom we have cited. We may add that the salts of mercury, of copper, and of lead, which, in combining with gelatine, form, it is true, an inalterable compound, have a great affinity for hydrosulphuric acid, and that there results from this affinity, a necessary deterioration of the objects, colouring them black. Sea salt does not possess durable preservative properties; and its affinity for water even facilitates the decomposition of the dried subjects which contain it. Alcohol is, doubtless, a good means, but it requires to be frequently renewed, until by its affinity for water it absorbs all which the organs contain; but alcohol costs forty cents a quart, and loses always by evaporation. Besides, parts thus prepared, are not less deformed than other dried parts, when subjected to desiccation.
The naturalist finds in the soap of Bècoeur, in other preparations containing arsenic, the deuto-chloride of mercury, alum, &c., sufficiently good means of drying or of tanning the skin and other animal tissues. But, as M. Boitard has remarked, these preparations are not without their inconveniences.
What have I to offer the anatomist who believes in the utility of dried preparations, to the naturalist whom a real necessity often forces to recur to them? My liquid, employed as a bath or injection, without either danger or inconvenience, and which costs only two or four cents the quart.
I shall give here an example of injection; a corpse is injected by the carotid with from five to seven quarts of the acetate of alumine at 20°, and containing in solution about two ounces (fifty grammes) of arsenic acid. Four days after this injection, if it is intended to prepare the large and small vessels, inject by the aorta half a quart of a mixture, equal parts, of the essence of turpentine and essence of varnish; finally, make a single cast of a hot injection of a mixture of suet and of rosin, in equal parts, coloured with cinabar for the arteries, and with a black or blue colour for the veins. Then, the corpse, or the part of the corpse which it is intended to preserve, is prepared and dissected at leisure, according to the wish of the operator.
When the body has been injected, as above described, the preparation which is made of it easily dries in the open air from the month of May to the month of October; during the winter it is necessary to deposit it in an oven, or in a heated chamber. When the desiccation is slow, or the moisture is excessive, the byssus sometimes develops on its surface, but this may be washed off, and a layer of varnish will prevent new vegetations. This preparation will be certainly superior to any contained in cabinets of anatomy.
In support of this assertion, I will cite an authentic fact, that of a woman whose body was submitted to the examination of the commissioners of the Institute and of the Royal Academy of Medicine, appointed to prove the value of my process.
On the 10th of May, 1834, a woman died in the wards of M. Majendie, at the Hôtel-Dieu; the body was injected the next day with the acetate of alumine; at the termination of this operation, it remained fresh until the 15th of January, 1835, when it dried without experiencing any alteration. The commissioners of the two Academies made experiments upon this body, at different periods. On the 15th of January, 1836, M. Guèneau de Mussy, to assure himself of the state of the cerebral substance, demanded the head to be opened, I profited by this occasion to take off the hairy scalp. The same day, M. Breschet, desiring to know what would result from the exposure of this corpse to the open air, it was suspended beneath the shed of the dissecting rooms (ècole pratique.)
Ten months after, in the month of November of the same year, it had not experienced any alteration. At this period, M. Gaucherant, inspecting overseer of the ècole pratique, wishing to terminate the experiment, the body was sent to the cemetery.
The right arm and forearm, the only parts remaining untouched, after the experiments of MM. the commissioners, were amputated by myself. I preserve this piece, as well as the hairy scalp; I can show them to anatomists to be compared with all the preparations obtained by other processes; none of them, I am convinced will be pronounced comparable to mine. The hairs remain so firmly attached to the scalp, that a strong pull will not detach them; I am quite sure that the injection has penetrated even to the capillary tubes of these organs; my experiments upon cats, dogs, and birds, have demonstrated the penetration of my liquid into the horny organs, hairs, or feathers, which clothe the skin of these animals. These facts will demonstrate all the services which it is capable of rendering naturalists. Finally, no process of tanning could give to the internal surface of the skin an aspect more satisfactory than that which offer other preparations deposited in my cabinet.
2. Preservation in liquids.—The different preservative liquids produce effects very different from the process of desiccation; however, all those employed up to the present day, possess serious inconveniences, as any one may be convinced by reading the very commendable passages which we have extracted from the pamphlet of M. Dumèril. We shall point out some others which he has omitted.
(a.) Nitric Acid, the only one of all the acids, that can be of any use to the anatomists, preserves well, it is true, the preparation of the nerves, hardening their structure, and increasing their nacreous white colour; but it deteriorates all the other structures, it dissolves the gelatine, softens the muscles, and deprives the bones of their calcareous salts; it cannot be other than deleterious to objects of pathological anatomy, and natural history.
(b.) Alcohol, is more serviceable than any other liquor in use, but its high price renders its employment almost impossible for objects of normal anatomy; it hardens and sensibly alters objects of pathological anatomy; and these alterations, however trifling they may be, and unimportant to regular anatomy, are serious for the physician, who cannot have too exact an idea of the progress of disorganization in the living tissues. If alcohol is eminently useful for natural history, its costliness renders it impossible to extend the use of it as far as the interest of science demands.
(c.) Diluted Alcohol, to which is added the deuto-chloride of mercury, is a less expensive liquor; it preserves accurately enough the labours of the naturalist and anatomist, but it is not sufficiently faithful for a pathological anatomy. The same may be said of the hydro-chlorate of soda, the hydro-chlorate of ammonia, the muriate and nitrate of alumine added to alcohol.
(d.) Alum, which we have seen figure in many of the adopted formulæ, is, nevertheless an unprofitable means of preservation. Extensively used in commerce, and employed from time immemorial in dyeing, it has only recently attracted the attention of preparers. This salt, to which the new chemical nomenclature has successively assigned the names of double sulphate, triple sulphate, acid sulphate of alumine and potash; has been experimented upon by myself, and has not answered my expectations. I have investigated the cause of this failure, and think I have found it; in analysing this compound, for every hundred parts I have obtained
| Sulphate of alumine, | 36 | .85 |
| Sulphate of potash, | 18 | .15 |
| Water, | 45 | |
| –— | ||
| 100 |
One hundred parts of this salt contains 10.86 of alumine. At the temperature of 12° centigrade, five hundred grammes of water dissolves thirty grammes of salt, from whence it results that a pound of water contains in solution only eighteen grains of alumine; from whence I have suspected that the little efficacy of alum for the preservation of animal matter, depends on the too small quantity of alumine in the solution. A fact convinced me that I was right: twenty-four hours after the immersion of a corpse in a bath containing the acid sulphate of alumine, I have observed that all the alumine was absorbed by the animal matter. Finally, the experiments which I have tried with the salts of alum, more rich in alumine, and more soluble in water, and the happy results I have attained, authorizes me to say: alum is a bad means of preservation, because it is not sufficiently soluble, and does not contain enough alumine. The reader will naturally again recur to the subject when we come to the exposition of my researches.
Sect. 3.—Means of preservation applied to each tissue.
In our first paragraph, we have passed in review the different preparations which ought to precede the application of preservative means; in the second, we have seen these numerous means, and we were compelled to deliver an impartial judgment. It remains for us to explain here how anatomists have applied them to the tissues taken separately. We shall abstain from relating the preparations which precede the application of preservative means, because they are foreign to the subject which occupies us, and would uselessly prolong a discussion already too much extended.
1. Fibrous tissues.—Articulations, aponeuroses, tendons, and ligaments.—The process generally adopted is due to M. J. Cloquet, in nearly following the method employed by the tanner, he has succeeded in preserving the suppleness of these tissues.
“The following,” continues he, “is the process which I have adopted.
“Dissolve four pounds of muriate of soda and a pound of alum in ten pints of water: the articulation, which has been carefully dissected, must be allowed to macerate fifteen or twenty days in this lie; paying attention to move it frequently in the solution, to press and twist its ligaments, and, above all, to strike it lightly with a little mace of light wood. These manœuvres are intended to render them pliable, to separate the fibres, which permits the salts to penetrate more easily. Withdraw the articulation from the solution, dry it for four or five days, taking care to move it occasionally, and still to strike it with the little mace; then put the articulation into a very concentrated solution of soap, (a pound to three pints of water,) handle, and strike it again for seven or eight days, the time necessary for divesting it of salt, and permitting the soap to penetrate the ligamentous fibres, to take the place of the salts. At the end of this time, that is to say, thirty-six or forty days after the commencement of the operation, wash the articulation in a weak lie of carbonate of soda, (an ounce to two pounds of water,) after which it is to be dried.
“By this process, which may be modified in various ways, ligament may be obtained perfectly supple, of a yellowish or grayish colour, resembling chamois leather, very resisting, and permitting the joints to execute their ordinary movements.
“I have prepared, in this manner, the articulations of the shoulder, of the knee, of the fingers, and of the vertebral column. I repeated my experiments with the intention of obtaining a more expeditious method.
“The articulations may also be preserved perfectly supple, by keeping them immersed in a mixture of equal parts of olive oil and essence of turpentine.
“2. Osseous tissue.—The different preparations to which bones are subjected in order to preserve them, are maceration or ebullition, and then bleaching.
“Maceration.—When it is desired to obtain the bones very white, it is necessary to choose, as far as possible, a thin or infiltrated corpse, of an individual of from thirty to forty-five years, or thereabouts, dead of some chronic disease which has not altered the structure of the bones. Consumptive bodies are the most proper for this kind of preparation. The subject being chosen, it is roughly stripped of its muscles and periosteum; the sternum is to be detached by dividing the costal cartilages where they join the ribs; the members are to be separated from the trunk, in order that these various parts may be more conveniently placed in a trough, which is to be filled with water, and disposed in some place where the putrid emanations cannot produce any inconvenience; the bones must be constantly kept covered with water, which must be renewed every four or five days in the commencement, and at more prolonged intervals towards the end of the maceration.
“The anatomist should watch over these macerations; and it is only when all the fibrous parts separate easily from the bones, or the inter-vertebral fibro-cartilages, and the yellow ligaments separate readily from the vertebra, that the skeleton should be withdrawn from the bath and cleaned. For this purpose, he collects with care all the pieces, and places them in clean water; he cleans them by removing with a scalpel the fibrous parts which may yet adhere, and by rubbing them under water with a very coarse brush; he then places them on coarse linen to dry them.
“Ebullition.—Boiling water is often resorted to for preparing the bones of the skeleton. After having roughly separated them from the soft parts, they are placed in a kettle of water, and subjected to ebullition for six or ten hours, according to the subject. The action of the water is increased, and the fibrous parts more accurately stripped from the bones, as well as the grease, by placing in the kettle, an hour before the end of the operation, potash, or soda of commerce, (sub-carbonate of potash, and of soda,) one pound to eighty or a hundred pints of liquid. After having carefully removed the grease which swims on the surface of the water, the bones are to be withdrawn and plunged into a new alkaline lie, warm and very weak; clean them with care, as in the preceding case, separating exactly from the articular surfaces, the swollen and softened cartilages, which remain adhering to them: the bones being clean, they are to be washed frequently previously to drying.
“In employing ebullition, we have the advantage of preparing the bones more promptly, and in a manner less insalubrious than by maceration. Nevertheless, this mode of preparation has its inconvenience: 1. Bones which are boiled, become, in general, less white than those which are macerated; the blood coagulating in their pores, leaves a brown tinge, which it is often impossible to remove; 2. They commonly retain a greater quantity of medullary matter, which, by becoming rancid, soon gives them a yellow colour and a very disagreeable odour; 3. Ebullition is not applicable to the bones of young subjects, in which the epiphyses are not yet adherent; it acts upon their gelatinous texture, and despoils, in part, the short bones and the extremities of the long bones of the compact layer which envelopes them. This last inconvenience is manifested even in the bones of adults.
“Dealbation, or bleaching of bones.—In order to obtain macerated bones perfectly white, several processes are employed: 1. The best method consists in placing them upon the grass exposed to the united action of the air, the sun, and the dew, as is practised in bleaching linen, wax, &c.; care is to be taken to turn them every fifteen days, in order that they may bleach equably; two or three months of such exposure is sufficient, particularly during the spring, to give them a brilliant whiteness. 2. The bones may be exposed to the action of chlorine, either liquid or gaseous. In the first case, they are to be plunged three or four times daily in a lie which holds chlorine in solution, repeating this operation for ten or twelve days; in the second, they must be steeped in water, placed on a hurdle and covered with cere-cloth or gummed taffeta, they are then to be exposed over an earthen pan, in which has been placed suitable proportions, of muriate of soda, oxide of manganese, and sulphuric acid: from time to time this mixture is to be slightly heated. 3. In place of gaseous chlorine, the vapour of sulphuric acid may be advantageously employed, as is done in the arts of bleaching wool, silk, &c.; sulphur is slowly burned beneath the hurdle, upon which has been placed the moistened bones; the alkaline lies may also be used for the bleaching of bones although they do not appear to me so advantageous as the preceding means.
“3. Cutaneous tissues.—Deprived of grease, and of subjacent cellular tissue and exposed to the air, this tissue inclines to dry. The human skin may be prepared by the aid of several processes analogous to those of tanners and leather dressers. A lie has been recommended composed of two pounds of common salt, four ounces of sulphate of iron, and eight ounces of alum, melted in three pints of almost boiling water; the skin divested of its grease, is plunged into this solution, agitated for half an hour, and macerated for a day or two in this liquid; the lie must be frequently renewed, then the skin is to be withdrawn from the bath and dried in the shade.
“4. Cellular tissue.—Authors have successively employed desiccation, insufflation, tanning liquors and alcohol, for preparing the cellular tissue; although the method given by them as preferable, is the preservation in an aqueous solution of nitrate of alumine, to which is added a small quantity of spirits of wine.
“5. Synovial and serous tissues.—The first is much more easily preserved than the other; an accurate dissection, expulsion of the synovial liquor, kneading, and desiccation, are the means used; the operation is finished by the application of a preservative varnish. The same practice is applied to the serous tissues, but with less success; its proximity to organs eminently putrescible, such as the brain, the lungs, the liver, renders its dissolution more imminent, more difficult to prevent.
“6. Encephalon, spinal marrow, nerves.—We have already spoken of the property of nitric acid, to give consistency to the nerves, without causing them to lose any thing of their pearly whiteness. Anatomists generally avail themselves, for the preservation of the whole nervous system, of the alcoholic solution of corrosive sublimate. After twenty or thirty days immersion in the bath, these organs are withdrawn and exposed to dry. As communicating a remarkable density to the encephalic mass, a solution of sugar in brandy is much praised: it is a method recommended by Lobstein, chief of the anatomical department of the Faculty of Strasbourg.
“7. Arterial vessels, veins, and lymphatics.—The interesting details which have been furnished to us by the pamphlets of M. Dumèril on the subject of injections, will enable us to dispense with much further developments; the vessels injected and preserved, as we have seen, are dried and preserved in alcoholic liquors.
“When the object is to prepare the vessels of the bones, some care is exacted to render visible their passage through the bony frame; after having filled the vessel with a coloured injection, the piece is to be placed in a diluted mineral acid, which, in dissolving the calcareous phosphate, leaves the vessels in position, and clearly visible through the gelatinous portion of the bone.
“In causing this mucous body to dry slowly and in the shade, it will acquire the necessary transparency to manifest on its cut surface (endued with volatile oil and varnished) the distribution of the vessels which penetrate the bones. These pieces may be preserved in a collection, either in the open air, after having been plunged into an alcoholic solution of arsenical soap, which dries quickly without bleaching; and to which essence varnish adheres very well; or if the piece is small, it may be suspended in a jar of volatile oil, luted with care; in this latter case, the injection must have been made with gelatine, and not with fatty matter.
“8. Muscular tissue.—The process of Swan, or rather the discoveries of Chaussier, furnish the means of preserving the muscles by desiccation. Nevertheless, another method is recommended by authors; after having prepared the vessels and the muscles, the preparation is to be placed in a mixture of alcohol, lavender, and essence of turpentine; it is to be left for several days in this liquor, and then exposed to a warm and dry air; when desiccation is complete, a layer of varnish may be applied.
“9. The preservation of particular organs, such as the heart, the lungs, the eye, &c., differ but little from that of the organs which we have just mentioned; they are always to be either dried, or deposited in an alcohol bath. The lacrymal ways, says M. Breschet in his excellent thesis on the preservation of anatomical subjects (Paris, 1819,) are less easily preserved, although the lacrymal sac, nasal canal, the lacrymal points and conducts, offer more difficulty in their preparation than in their preservation, which may be accomplished by liquors, or by desiccation. The lacrymal canal, and its excretory canals, can only be seen on preparations in spirits of wine. Finally, the following are some passages from the same work, upon the means of preserving the embryon and the fœtal envelopes.
“It is useful to preserve the embryons and fœtuses at different periods of gestation, in order to study the successive development of each organ.
“The egg, considered in its various periods of incubation, can only be preserved in alcohol somewhat weakened, in order that it may not harden the membranes. Kirschwasser, in which has been dissolved the nitrate of alumine, forms a limpid liquor, in which the egg may be preserved without any alteration. In order to demonstrate the development of these organs, many parts may be injected; thus, during the earlier periods, the pedicle of the umbilical vesicle admits mercury, which is introduced by a small glass syringe, the tube of which has been drawn fine in the blow-pipe: this injection ought to be made on the side of the vesicle, and sometimes the metal may be seen passing into the intestines.
“The omphalo-mesenteric vessel ought also to be injected. The urachus should be opened, and its communication with the bladder should be shown on one part, and with the alantois on the other. All these parts are to be kept separate from each other, and attached by means of small pins to a plate of wax. In the fœtus, near the term of gestation, those vessels which establish the communication between it and the mother, are to be injected.
“The bones of the embryon, after having been injected, are to be placed in oil of turpentine, without its being necessary previously to place them in a weakened acid.
“As regards the envelopes of the fœtus, and the placenta which it may be intended to preserve after an accouchment at full term, injections of different colours are forced into the umbilical arteries and veins; this injection should not be too delicate, or pushed with too much force, otherwise it will pass from one of the vessels into the other. These two parts should be allowed to soak some time in an aluminous water, or, what is better, in a sublimated alcoholic solution, then place a hog’s bladder in the cavity of the membranes, blow up the bladder, and thus expose the parts to the air for desiccation; after which the bladder is to be withdrawn. The membranes, with the placenta, may thus be preserved, by placing the uterine face of the latter sometimes within sometimes without the cavity of the membranes. These same parts can be preserved in liquors. Finally, some persons make use of the method of corrosion to prepare and preserve the placenta.”
It is useless to advance here new observations; those which have been already presented on the occasion of preservation, considered in general, are equally applicable to the present. It will be perceived in the following chapter what means I propose to substitute for them, as meriting the preference.