PART VI. 



THE PROTOZOA, OR ANIMAL PARASITES. 



AMGEBA COLI. 



Found in the human intestines, in the stools, in dysentery, and 

 in the diarrhoea in abscess of the liver. 



Microscopical Appearances. During the resting stage they 

 appear as almost homogeneous cells, while during motility a slightly 

 refractive ectoplasm and strongly refractive entoplasm with a granular 

 appearance can be distinguished. Vacuoles are also frequently present 

 in the entoplasm, as well as foreign bodies, red blood-corpuscles, and 

 bacteria. The large nucleus, with a nucleolus, is plainly visible in dead 

 forms, stained specimens, or by the addition of acetic acid. 



Motility. This is due to the presence of pseudopodia, in which 

 rounded blunt continuations of the ectoplasm extend into the entoplasm. 



The Amoeba coli multiply by dividing in two. All attempts at 

 cultivation have up to the present failed. The Amoeba coli found in the 

 normal intestinal contents cannot be distinguished morphologically from 

 that found in dysentery, but the latter, when introduced into the rectum 

 of cats, causes an ulcerative haemorrhagic inflammation of the large 

 intestines. Furthermore, the dysentery amoeba are genuine tissue 

 parasites, penetrating deep into the submucous, sometimes as far as the 

 serous coating of the intestines. 



Method of Examining Stools for Bacteria. The stool for exa- 

 mination should be quite recent, and should, if possible, be received 

 in a vessel previously warmed to body-heat. In a watery stool a drop is 

 taken, preferably from the red jelly-like part showing bloody mucus, and 

 examined on a cover-glass. If more solid but unformed, the stool is 

 diluted with warm normal saline solution, and treated as above. 



In solid formed stools some of the mucous slime attached is examined. 

 In making a permanent preparation some of the material is smeared 

 very thinly on the cover-glass, and before there is time for drying it is 

 passed into absolute alcohol to fix. Their staining reactions are not as 

 pronounced as those of the bacteria, and methylene blue gives the best 



