ANIMAL PARASITES 



til 



(4) a thick outer, deeply staining layer of muscles. Examining 

 the base of the glandular portion under high power note the 

 numerous rounded, vacuolated amoebae. The structure of their 

 nuclei is not typical as they are rarely fixed in a favorable manner. 



Fig. 20. — Amoebae of man. la-lc, Endamceba histolytica; 2a-2d, Endamceba 

 coli; 3, Councilmania lafeuri cyst with "bud;" 4a-4b, Iodamaeba ivilliamsi; 5a-5d, 

 Endolimax nana; 6, Dientamcebafragilis; 7, Endamceba gingivalis. (After Kofoid, 

 except la and 5 after Boeck, 2b, 2c and 4 after Wenyon.) 



Cysts. — Search the prepared slides under high power for the 

 round, four-nucleate mature cysts of Endamveba histolytica. 

 They are sharply contoured, spherical bodies measuring from 

 5 to 20/j. in diameter, whose nuclei show the typical delicate 

 peripheral layer of chromatin and the central karyosome. In 

 addition, about half of the cysts show one or more conspicuous 

 black, rod-like bodies with rounded ends, which, like the chro- 

 matin of nuclei, stain black with the iron-hsematoxylin stain. On 

 account of this reaction they are called chromatoid bodies. In the 

 same preparation will be found uninucleate and binucleate cysts. 

 These contain one or more large glycogen masses which in fresh 

 cysts stain a deep mahogany color in iodine. Make careful 

 drawings of the various stages of cysts found. 



