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GUIDE TO THE STUDY 



For the examination of unstained cysts, formalin-preserved 

 fecal material showing those of Endamceba coli will be used, since 

 this species is more readily available than is E. histolytica. 

 Mount a small drop of the sedimented material under a cover 

 glass. Care should be taken not to use so much as to render the 

 mount opaque. (A satisfactory preparation should be so trans- 

 parent that ordinary print can be read through it.) Search for 

 round, sharply contoured clear bodies, usually about twice the 



Fig. 20a. —Section of rectum of kitten infected by Endamceba histolytica, showing 

 groups of the rounded parasites at the base of the crypts. (Orig.) 



diameter of a red blood corpuscle. Add a drop of iodine solution 

 and study under high power. The nuclei are brought out by 

 the iodine and it will be seen that they are eight in number in the 

 mature cysts as contrasted with four for those of E. histolytica. 

 The karyosome is large and excentric and the peripheral chro- 

 matin, along the nuclear membrane, is thicker. 



Preparations stained in iron hematoxylin frequently show 

 splinter-like chromatoid bodies, in contrast to the rounded ones 

 of E. histolytica. 



Endamoeba coli. Amoeboid Forms. — Study the prepared slide 

 of Endamceba coli and note that the peripheral chromatin of the 

 nucleus is in a thicker layer and its granules coarser than in E. 

 histolytica. The karyosome is coarser and excentric in position. 



