| Introduction | [11] |
| On Cutting Unprepared Vegetable Tissues | [12] |
| On Cutting Unprepared Animal Tissues | [13] |
| Preparation of Vegetable Tissues | [15] |
| Preparation of Animal Tissues | [16] |
| Special Methods of Hardening | [19] |
| Cutting Hardened Tissues by Hand | [19] |
| Microtome | [20] |
| Æther Microtome | [24] |
| Section-Knife | [24] |
| Imbedding in Paraffine for Microtome | [26] |
| Employment of Microtome | [29] |
| Staining Agents | [31] |
| Carmine Staining | [32] |
| Mounting Media | [36] |
| Mounting in Glycerine | [38] |
| Uses of Freezing Microtome | [42] |
| Employment of Freezing Microtome | [43] |
| Logwood Staining | [47] |
| Absolute Alcohol | [50] |
| Clove Oil | [51] |
| Canada Balsam | [51] |
| Mounting in Balsam | [53] |
| Finishing the Slide | [55] |
PART II.
| Special Methods | [57] |
| Bone | [57] |
| Brain | [59] |
| Cartilage | [60] |
| Coffee Berry | [62] |
| Fat | [63] |
| Hair | [63] |
| Horn, etc. | [64] |
| Intestine | [64] |
| Liver | [65] |
| Lung | [65] |
| Muscle | [66] |
| Orange-peel | [67] |
| Ovary | [67] |
| Porcupine Quill | [67] |
| Potato | [67] |
| Rush | [68] |
| Skin | [68] |
| Spinal Cord | [69] |
| Sponge | [71] |
| Stomach | [71] |
| Tongue | [71] |
| Vegetable Ivory | [72] |
| Wood | [72] |
| Note A, | [75] |
| Note B, | [75] |
| Note C, | [76] |
| Note D, | [76] |
| Note E, | [76] |
| Note F, | [77] |
| Note G, | [77] |
| Note H, | [93] |
| Note I, | [94] |
| [Index] |
SECTION-CUTTING.
PART I.
1. Introduction.—Many of the most interesting objects with which the microscopist has to deal, cannot be made to reveal their beauty or minute structure until they have been cut into slices or sections, of such a degree of thinness as to render them transparent, and thus permit of their examination by transmitted light, with objectives of varying power. Unfortunately, however, very few of the objects of this class are, in their natural condition, in a suitable state to be submitted to this method of procedure. Some are of such a soft and yielding nature that any attempt to cut them is an utter failure, for in place of a perfect section being obtained, nothing remains upon the knife but a mass of diffluent pulp; others, again, are of such density as to resist the action of any cutting instrument.
It is evident, therefore, that nothing can be done with such refractory materials until, by subjection to appropriate methods of preparation, they shall have been reduced to such a consistence as to render them suitable for cutting. How this is to be accomplished will depend entirely upon the physical and chemical nature of the substance to be operated upon. As the various objects differ so widely from each other in these respects, so must the methods of preparation suitable to each also vary. It is clear, therefore, that no general directions for attaining this end can be given which would be of any practical value. It is possible, however, and very convenient, to arrange the various objects into groups or classes, to the treatment of each of which certain general rules are applicable; but there will still remain a comparatively numerous series of objects whose individual peculiarities of structure will demand for them correspondingly special methods of preparation. When such objects come to be spoken of, the particular treatment most suitable to each will also be noticed.
2. On Cutting unprepared Vegetable Tissues.—There are some few substances, however, which may with more or less success be cut into sections whilst in their natural condition. Such objects are to be found in the vegetable world in certain kinds of leaves and allied structures, whilst in the animal kingdom they are principally represented by the various internal organs of man and the lower animals. Special directions are given in text-books for the preparation of sections of leaves and similar substances. For instance, it is recommended to lay the leaf, etc., on a piece of fine cork, and with a sharp knife to shave off thin slices, cutting down upon the cork. Another plan is to place the leaf, etc., between two thin layers of cork, and cut through the mass. No method, however, is at once so simple and successful as the process of imbedding in paraffine. To do this, it is necessary to make a paper mould by twisting a strip of stout writing paper round a ruler, and turning-in the paper over the end of the ruler. This mould, the height of which may vary from an inch to an inch and a half, should now be about half filled with melted paraffine mixture (§ 11), the leaf or other object plunged into it, and held in position by small forceps till the paraffine has become sufficiently solidified to yield it a support. More of the paraffine mixture is now poured in until the specimen is thoroughly imbedded; the whole is to be put away in a cold place for an hour or so, when the mass will be found sufficiently firm to be cut with ease. Sections may be made with a razor kept constantly wetted with water, or, if the preservation of colour be no object, methylated spirit may be employed for the purpose. As the subsequent treatment of such sections in no wise differs from that required by those cut in the microtome, we shall defer its consideration until that method of section has been described (§ 12).