HISTOLOGICAL DEMONSTRATIONS. 115 



occupying the intervals above and below them, smaller 

 cells of irregular shape. The former have long been 

 termed "peptic" cells. By Heidenhain they have been 

 named " parietal," while the others have been termed by 

 him the "chief" cells, from his supposing that they are 

 especially concerned in the secretion of gastric juice. 

 About the middle of the follicle the " parietal " cells form 

 an almost continuous layer. 



In a V. S. of stomach, near its pyloric orifice, glands, 

 lined throughout by columnar epithelium, may be seen. 

 These are commonly termed mucous glands. They occur, 

 though in relatively small numbers, throughout the re- 

 mainder of the stomach. 



THE INTESTINE. 



191. Methods. a. The intestine may be hardened 

 in a solution of chromic acid and potassium bichromate, 

 followed by alcohol, as described in 7. Sections of the 

 small intestine are best made in the freezing microtome, for 

 the villi are apt to be spoiled by paraffin or any similar im- 

 bedding agent. The sections unstained are mounted in 

 Farrants' solution or in glycerine, or they may be stained 

 with logwood or carmine, and mounted in the same fluids or 

 in dammar. 



b. A method devised by Klein gives good results. Place portions 

 of the intestine in a mixture of two parts of \ per cent solution of 

 chromic acid, and one part of methylated alcohol. Change the fluid 

 two or three times, and at the end of seven days transfer to dilute 

 spirit (methylated spirit I, water 2 parts). After two or three days 

 place them in methylated spirit, and when they are sufficiently hard 

 make sections. Place the sections for a few minutes in I per cent 

 sodium bicarbonate solution, and then stain them with logwood. 



c. Auerbach's plexus between the two layers of the muscular coat 

 may be thus prepared. (Klein.} Take the small intestine of a rabbit 

 just killed, and, after washing out its contents with a stream of salt 

 solution, innate it with air. With broad-pointed forceps strip off the 

 longitudinal layer of muscular fibres in as membranous a form as pos- 

 sible. Place the membranes thus detached in \ per cent chloride of 

 gold solution for twenty-five minutes ; wash in distilled water, and after- 

 wards treat as stated in 330. 



d. The openings of the chalice cells may be rendered very distinct 

 by the silver process already described in 96. 



