4. _Preparation of Vegetable Tissues._—Let us now pass to a brief consideration of the methods usually adopted for preparing the various objects for easy section. In the case of _vegetable_ tissues, not only do we, as a rule, find their texture of too great density to be readily cut in their natural condition, but they also contain much resinous and starchy matter, of which it is highly desirable to get rid. In order to do this we first cut the substance (say a stem or root) into small pieces, which are to be placed in water for three or four days, by which time all the soluble gummy matters will have disappeared. The pieces are now transferred to a wide-necked bottle, containing methylated spirit,[2] which, in the course of a few days, will dissolve out all the resin, etc. Many kinds of woody tissue are by these processes reduced to a fit condition for immediate cutting; others, however, are so hard as to render it necessary to give them another soaking for some hours in water, to bring them to a sufficient degree of softness to cut easily. If the wood (as in some few refractory cases will happen) be still too hard for section, a short immersion in warm, or if necessary, in boiling water, will not fail effectually to soften it. The treatment of such members of the vegetable division as require peculiar methods, will be found described in future pages. Footnote 2: Note B. 5. _Preparation of Animal Tissues._—_Animal_ tissues differ from one another so greatly, both in consistence and in chemical composition, as well as in their degree of natural hardness, that no general rules can be given which would be applicable to the preparation of the whole class. Such as are of any considerable degree of hardness, as horn and kindred structures, must be treated much in the same manner as the denser varieties of wood, viz., by more or less prolonged immersion in water—cold, hot, or boiling. Those which are of extreme hardness, as bones and teeth, can be cut only by following certain special methods, full details of which will be found in the Second Part of this work (§ 26). Many, and indeed the vast majority of animal tissues, offer a direct contrast in point of hardness to those we have just been considering. All the internal organs of the body are, when freshly removed, of much too soft a nature to permit, when in their unprepared condition, of easy or perfect cutting. It is upon bringing them to that critical degree of hardness, which is often so difficult to attain, that the chief secret of successful section-cutting depends; for unless the hardening process has been carried up to, but not beyond, a given point, which varies with different tissues, the operator, however dexterous, will fail to obtain satisfactory sections. For, if the hardening has fallen short of this critical point, he is, to some extent, in the same position as if he were dealing with unhardened tissues; whilst, if this