*Normal histology.*--It cannot be too strongly impressed on the beginner that a thorough mastery of the normal appearances of tissues and organs is absolutely necessary before attempting to make an accurate study of morbid changes in them. He should not be satisfied with examining one specimen of an organ but as many as he conveniently can, in order to be fully acquainted with the many deviations from normal which may exist without actual disease. He should therefore obtain several animals, such as small dogs, cats, rabbits, frogs, &c., and remove their organs with all care, and harden them in the various appropriate fluids. He should also obtain specimens of normal human organs from the post-mortem room. Many normal tissues (skin, muscle, tendon, bone, &c.), can also be prepared from a limb amputated for an accident to a healthy patient. By preparing specimens in this way he will not only become the possessor of a set of slides illustrating normal histology, but will find also that he has acquired that proficiency in hardening and staining the specimens which practice alone can give. The following account of the method of preparing different tissues is merely intended to indicate the lines on which the beginner should proceed. After some practice he will be quite able to select the modes of hardening and staining which special circumstances or cases may seem to demand. The first part of these directions will refer to the preparation of normal tissues, the second part to morbid histology. *Blood.*--For special methods of examination see Chapter VII. *Blood crystals--Hæmoglobin crystals*, obtained from the blood of an animal, or enough may be collected at any operation. A little water or a little ether is added to the blood which is allowed to stand for half-an-hour after which a drop is allowed to evaporate slowly on a clean slide. *Hæmatin crystals.*--The student should make himself thoroughly familiar with these, as their presence affords positive proof of the existence of blood colouring matter in a stain. To obtain them a drop of blood should be allowed to dry on a slide. The dried blood is scraped into a little heap with a small piece of clean glass, and a drop of glacial acetic acid added. As it evaporates minute reddish-brown acicular crystals will appear. *Hæmatoidin crystals.*--Obtained from the site of a bruise, or an old hæmorrhage, _e.g._, a cerebral apoplexy or a hæmatocele. *Simple squamous epithelium.*--(_Endothelium_). Carefully strip off the lining of the parietal pericardium or parietal pleura, of a recently killed animal, or spread out its omentum on a piece of cork, and (1) stain the intercellular cement with nitrate of silver (p. 82) so as to reveal the outlines of the cells. (2) Stain other specimens with hæmatoxyline or alum carmine to reveal the nuclei. *Stratified squamous epithelium.*--Specimens from skin of various parts, finger, groin, lip, tongue should be prepared. Harden in Müller’s fluid.