Stain

sections in A, then in B. The blue of the nuclei will be altered to red and the bacteria will remain blue. Weigert's Gentian-violet. Gentian-violet 2 gm., ammonium hydroxid 0.5 c.c, distilled water 90 c.c., absolute alcohol IO c.c.; mix and filter. Ziehl's Fuchsin. Filtered, saturated, aqueous solution of carbolic acid 90 parts, saturated alcoholic solution of fuchsin 10 parts. Used for staining the typhoid bacillus. Ziehl's or Ziehl-Neelsen's Solution. See Staining of Microorganisms, Kiihne ' s Fuchsin. ZOOLOGIC METHODS. Vnnelids. The blood-ve els of annelids may be demonstrated by treating them for 2 or 3 hours with aqua regia. The animals should be laid open before being put into the mixture. The ve el-walls appear black on a yellow ground. The nerves may be brought to view by staining with methylene-blue (see Staining Reagents). Ehler's fluid (see Fixing Fluids) is recommended for fixing and hardening. The intestine of Lumbricus may be cleansed by putting the animal into a tall gla jar filled with scraps of moistened blotting-paper they; gradually evacuate the earthy contents of the gut and fill it with paper (Kukenthal). Coffee grounds may be used instead of paper, and are said to cut better when embedded. The animals may be narcotized them for an hour to the vapor of chloroform; if exposed for a longer period they will die in a state of extension. Eyes of Arthropods. Hickson's Method. Remove the posterior wall of the head of a fly, and expose the rest to osmium vapor for 20 minutes; wash in per cent. alcohol, harden in absolute alcohol, and make sections. Fix sections to the slide with Mayer's albumin (see Fixatives), remove the paraffin with turpentine, wash with absolute alcohol, and decolorize by inverting the slide over a capsule containing 90 per cent, alcohol to which a few drops of nitric acid have been added; wash with pure alcohol. Parker's Method. For the eye of Homarus. Make paraffin sections and fix them to the slide with Schallibaums collodion, treat with alcohol, then with water, and then for a minute with a o. 1 per cent. solution; wash thoroughly, and stain for 3 hours in Weigert's hematoxylin (see Staining Reagents) at a temperature of 500 C.; wash, dehydrate, and mount in balsam. Eyes of Gastropods. Carriere's Method.