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.
Transitional epithelium.—Occurs in the pelvis of the kidney, ureter and bladder. It is very readily detached, especially if not hardened immediately after death. Remove as early as possible. If the bladder is taken it should be cut open and pinned out as flat as possible. Harden in osmic acid, or Müller’s fluid and spirit. Embed preferably in celloidin.
Simple columnar epithelium.—Occurs in many parts. It may be studied in the salivary ducts, the intestine, kidney, &c., of any mammal.
Goblet-cells.—Seen abundantly among the columnar cells of the intestinal glands, and in the mucous glands of the mouth and of the cervix uteri.
Stratified columnar epithelium.—Occurs only in the urethra. Harden the penis of a cat in Müller’s fluid, and cut transverse sections.
Ciliated epithelium.—Harden the trachea of a recently killed cat in osmic acid or Müller’s fluid. Beautiful specimens may also be obtained from an ordinary nasal polypus, which should be put into hardening fluid immediately after removal.
Stain all sections of epithelium in picrocarmine, and in eosine and hæmatoxyline.
Ordinary areolar tissue.—Difficult to obtain free from fat. It may be studied in the subcutaneous tissue of the section of the cat’s penis already made. A fragment of the tissue should also be removed and carefully teased in a drop of picrocarmine. Areolar tissue may also be studied in sections of skin, and in the capsules of the different internal organs.