EXERCISE THE FIFTY-SEVENTH.
Of certain paradoxes and problems to be considered in connexion with this subject.
Thus far have we spoken of the order of generation, whereby the differences between those creatures that are engendered by metamorphosis and those that are developed by epigenesis, as well as between those that are said to proceed from a worm and those that arise from an egg, have been made to appear. The latter are partly incorporated from a prepared matter, and are nourished and increased from a certain remaining matter; the former are incorporated from the whole of the matter present; the latter grow and are formed simultaneously, and after their birth continue to wax in size and finally attain maturity; the former increase at once, and from a grub or caterpillar grow into an aurelia, and are then produced, consummately formed, as butterflies, moths, and the like. Wherefore Aristotle, as Fabricius[299] observes: “As he assigns a sort of twofold nature to the egg, and a twofold egg in this kind, so does he assert a twofold action and a twofold animal engendered. For,” he proceeds, “from the first eggs, which are the primordia of generation, a worm is constantly produced; viz.: from the eggs of flies, ants, bees, silkworms, &c., in which some fluid is contained, and from the whole of which fluid the worm is engendered; but from the second eggs, formed by the worms themselves, butterflies are engendered and disclosed, viz.: flying animals contained in a shell, or follicle, or egg, which shell giving way the winged creature escapes; precisely as Aristotle[300] has it where he speaks of the egg of the locust.” Finally, whilst the higher animals produced from eggs are perfected by a succession of parts, the lower creatures that arise in this way, or that are formed by metamorphosis, are produced at one effort, as it were, and entire. And in the same way are engendered both those creatures that are said to arise spontaneously, by chance or accident, and derive their first matter or take their origin from putrefaction, filth, excrement, dew, or the parts of plants and animals, as well as those that arise congenerately from the semen of animals. Because this is common to all living creatures, viz.: that they derive their origin either from semen or eggs, whether this semen have proceeded from others of the same kind, or have come by chance or something else. For what sometimes happens in art occasionally occurs in nature also; those things, namely, take place by chance or accident which otherwise are brought about by art. Of this Aristotle[301] quotes health as an illustration. And the thing is not different as respects the generation, in so far as it is from seed, of certain animals: their semina are either present by accident, or they proceed from an univocal agent of the same kind. For even in fortuitous semina there is an inherent motive principle of generation, which procreates from itself and of itself; and this is the same as that which is found in the semina of congenerative animals,—a power, to wit, of forming a living creature. But of this matter we shall have more to say shortly.
From what has just been said, however, several paradoxes present themselves for consideration. For when we see the cicatricula enlarging in the egg, the colliquament concocted and prepared, and a variety of other particulars all tending, not without foresight, to the development of the embryo, before the first rudiment or the merest particle of this is conspicuous, what should hinder us from believing that the calidum innatum and the vegetative soul of the chick are in existence before the chick itself? For what is competent to produce the effects and acts of life, except their efficient cause and principle, heat, namely, and the faculty of the vegetative soul? Therefore it would seem that the soul was not the act of the organic body possessing life in potentia; for we regard the chick with its appropriate form as the consequence of such an act. But where can we suppose the form and vital principle of the chick to inhere save in the chick itself? unless indeed we admitted a separation of forms and conceded a certain metamorphosis.
Now this appears most obviously where the same animal lives, as Aristotle has it, by or under a succession of forms, for example, a caterpillar, a chrysalis, a butterfly. For it is of necessity the same efficient, nutrient, and conservative principle that possesses each of these, although under different forms; unless we allow that there is one vital principle in the youth, another in the man, a third in the aged individual, or maintain that the forms of the grub and caterpillar are the same as those of the silkworm and butterfly. Aristotle has entered very fully into this subject, and we shall ourselves have more to say on it immediately.
It appears further paradoxical to maintain that the blood is produced, and moves to and fro, and is imbued with vital spirits, before any sanguiferous or locomotive organs are in existence. Neither is it less new and unheard-of to assert, that sensation and motion belong to the fœtus before the brain is formed; for the fœtus moves, contracting and unfolding itself, when there is nothing more than a little limpid water in the place of the brain.
Moreover, the body is nourished and increases before the organs appropriated to digestion, viz. the stomach and abdominal viscera, are formed. Sanguification, too, which is entitled the second digestion, is perfect before the first, or chylification, which takes place in the stomach, is begun. The excrementitious products of the first and second digestions, namely, excrement in the intestines, urine and bile in the urinary and gall bladder, are contemporaneous with the existence of the concocting organs themselves. Lastly, not only is there a soul or vital principle present in the vegetative part, but even before this there is inherent mind, foresight, and understanding, which from the very commencement to the being and perfect formation of the chick, dispose and order and take up all things requisite, moulding them in the new being, with consummate art, into the form and likeness of its parents.
In reference to this subject of family likeness, we may be permitted to inquire as to the reason why the offspring should at one time bear a stronger resemblance to the father, at another to the mother, and, at a third, to progenitors, both maternal and paternal, further removed? particularly in cases where at one bout, and at the same moment, several ova are fecundated. And this too is a remarkable fact, that virtues and vices, marks and moles, and even particular dispositions to disease are transmitted by parents to their offspring; and that while some inherit in this way, all do not. Among our poultry some are courageous, and pugnaciously inclined, and will sooner die than yield and flee from an adversary; their descendants, once or twice removed, however, unless they have come of equally well-bred parents, gradually lose this quality; according to the adage, “the brave are begotten by the brave.” In various other species of animals, and particularly in the human family, a certain nobility of race is observed; numerous qualities, in fact, both of mind and body, are derived by hereditary descent.
I have frequently wondered how it should happen that the offspring, mixed in so many particulars of its structure or constitution, with the stamp of both parents so obviously upon it, in so many parts, should still escape all mixture in the organs of generation; that it should so uniformly prove either male or female, so very rarely an hermaphrodite.
Lastly, many things are present before they appear, and some are begun among the very first which are completed among the very last, such as the eyes, the organs of generation, and the beak.
Several doubts and difficulties have thence arisen as to the principality and relative dignity of the several members, in which they who are fond of such things have displayed their ingenuity. Among the number: whether the heart gives life and virtue to the blood; or, rather, the blood to the heart. Whether the blood be extant for the sake of the body as matter, nourishment, and instrument; or, on the contrary, the body and its parts are the cause of the blood, and constituted for the sake of the vital principle which especially inheres in it. In like manner, whether the auricles or the ventricles of the heart are the chief, the auricles being the first to live and pulsate, the last to die. Further, whether the left ventricle, which in man is of greater length, and is also surrounded with thicker and more fleshy walls, and is regarded as the source of the spirits, be hotter, more spirituous, excitable, and excellent, than the right, which contains a larger quantity of blood, and is the last to become unstrung by death; in which the blood of the dying accumulates, congeals, and is deprived of life and spirit; to which, moreover, as to a fountain head, the first umbilical veins bring their blood, and from which they themselves derive their origin.
So much appears from careful observation of the order observed in the production of the parts, and certain other points that follow as deductions from these, and do not a little militate against the commonly received physiological doctrines, viz.: since it is manifest that sensation and motion exist before the brain, all sensation and motion do not proceed from the brain; from our history it is clearly ascertained that sense and movement inhere in the very first drop of blood produced in the egg, before there is a vestige of the body. The first scaffolding or rudiment of the body, too, which we have said is merely mucilaginous, before any of the extremities are visible, and when the brain is nothing more than a limpid fluid, if lightly pricked, will move obscurely, will contract and twist itself like a worm or caterpillar, so that it is very evidently possessed of sensation.
There are yet other arguments deduced from sense and motion whence we should infer that the brain was not so much the first principle of the body, in the way the medical writers maintain, as the heart, agreeably to Aristotle’s view.
The motions and actions which physicians style natural, because they take place involuntarily, and we can neither prevent nor moderate, accelerate nor retard them by our will, and they therefore do not depend on the brain, still do not occur entirely without causing sensation, but proclaim themselves subject to sense, inasmuch as they are aroused, called forth, and changed thereby. When the heart, for example, is affected with palpitation, tremor, lipothymia, syncope, and with great variety in the extent, rapidity, and order or rhythm of its pulsations, we do not hesitate to ascribe these to morbific causes implicating, deranging its sensation. For whatever by its divers movements strives against irritations and troubles must necessarily be endowed with sensation.
The stomach and bowels, disturbed by the presence of vitiated humours, are affected with ructus, flatus, vomiting, and diarrhœa; and as it lies not in our power either to provoke or to restrain their motions, neither are we aware of any sensation dependent on the brain which should arouse the parts in question to motions of the kind.
It is truly wonderful to observe the effect of taking a solution of antimony, which we neither distinguish by the taste, nor find any inconvenience from, whether in the swallowing or the rejection. Nevertheless there is a certain discriminating sense in the stomach which distinguishes what is hurtful from what is useful, and by which vomiting is induced.
Nay, the flesh itself readily distinguishes a poisoned wound from one that is not poisoned, and on receipt of the former contracts and condenses itself, whereby phlegmonous tumours are produced, as we find in connexion with the stings of bees, gnats, and spiders.
I have myself, for experiment’s sake, occasionally pricked my hand with a clean needle, and then having rubbed the same needle on the teeth of a spider, I have pricked my hand in another place. I could not by my simple sensation perceive any difference between the two punctures; nevertheless there was a capacity in the skin to distinguish the one from the other; for the part pricked with the envenomed needle immediately contracted into a tubercle, and by and by became red, and hot, and inflamed, as if it collected and girded itself up for a contest with the poison for its overthrow.
The sensations which accompany affections of the uterus, such as twisting, decubitus, prolapse, ascent, suffocation, &c., and other inconveniences and irritations, do not depend on the brain or on common sensation; yet neither are these to be presumed as happening without all consciousness. For that which is wholly without sense is not seen to be irritated by any means, neither can it be stimulated to motion or action of any kind. Nor have we any other means of distinguishing between an animate and sentient thing and one that is dead and senseless than the motion excited by some other irritating cause or thing, which as it incessantly follows, so does it also argue sensation.
But we shall have an opportunity of speaking farther of this matter when we discuss the actions and uses of the brain. Respect for our predecessors and for antiquity at large inclines us to defend their conclusions to the extent that love of truth will allow. Nor do I think it becoming in us to neglect and make little of their labours and conclusions who bore the torch that has lighted us to the shrine of philosophy. I am, therefore, of opinion that we should conclude in this way: we have consciousness in ourselves of five principal senses, by which we judge of external objects; but we do not feel with the same sense by means of which we are conscious that we feel—seeing with our eyes, we still do not know by them that we see, but by another sense or sensitive organ, namely, the internal common sensation or common sensorium, by which we examine those things that reach us through each of the external sensoria, and distinguish that which is white from that which is sweet or hard. Now this sensorium commune to which the species or impressions of all the external instruments of sensation are referred, is obviously the brain, which along with its nerves and the external organs annexed, is held and esteemed to be the adequate instrument of sensation. And this brain is like a sensitive root to which a variety of fibres tend, one of which sees, another hears, a third touches, and a fourth and a fifth smell and taste.
But as there are some actions and motions the government or direction of which is not dependent on the brain, and which are therefore called natural, so also is it to be concluded that there is a certain sense or form of touch which is not referred to the common sensorium, nor in any way communicated to the brain, so that we do not perceive by this sense that we feel; but, as happens to those who are deranged in mind, or who are agitated to such a degree by violent passion that they feel no pain, and pay no regard to the impressions made on their senses, so must we believe it to be with this sense, which we therefore distinguish from the proper animal sense. Now such a sense do we observe in zoophytes or plant-animals, in sponges, the sensitive plant, &c.
Wherefore, as many animals are endowed with both sense and motion without having a common sensorium or brain, such as earthworms, caterpillars of various kinds, chrysalides, &c., so also do certain natural actions take place in the embryo and even in ourselves without the agency of the brain, and a certain sensation takes place without consciousness. And as medical writers teach that the natural differ from the animal actions, so by parity of reason does the natural sense of touch differ from the animal sense of touch,—it constitutes, in a word, another species of touch; and whilst the one is communicated to the common sensorium, the other is not so communicated.
Further, it is one thing for a muscle to be contracted and moved, and another for it by regulated contractions and relaxations to perform any movement, such as progression or prehension. The muscles or organs of motion, when affected with spasms or convulsions from an irritating cause, are assuredly moved no otherwise than the decapitated cock or hen, which is agitated with many convulsive movements of its legs and wings, but all confused and without a purpose, because the controlling power of the brain has been taken away:—common sensation has disappeared, under the controlling influence of which these motions were formerly coordinated to progression by walking or to flight.
We therefore conceive the fact to be that all the natural motions proceed from the power of the heart, and depend on it; the spontaneous motions, however, and those that complete any motion which physicians entitle an animal motion, cannot be performed without the controlling influence of the brain and common sensation. For inasmuch as by this common sensation we are conscious of our perceptions, so also are we conscious that we move, and this whether the motion be regular or otherwise.
We have an excellent example of both of these kinds of motion in respiration. For the lungs, like the heart, are continually carried upwards and downwards by a natural movement, and are excited by any irritation to coughing and more frequent action; but they cannot form and regulate the voice, nor can singing be executed, without the assistance, and in some sort the command, of the sensorium commune.
But these matters will be more fully handled when we come to speak of the actions and uses of the brain, and to consider the vital principle or soul. So much we have thought fit to say by the way, that we might show the respect in which we hold our illustrious teachers, and our anxiety to carry them along with us in our labours.