446 /. A. Gilruth and L. B Bull: 



amount of endoplasm surrounding innumerable nuclei, which in 

 the earlier stages are irregularly distributed, but in the later 

 stages are arranged around masses of protoplasm. Within the 

 endoplasm, lying close to the envelope of each cyst, at the pole 

 furthest from its neighbours, lies an irregularly spherical, oval 

 or crescentic deeply-staining granular body, which is probably 

 the greatly hypertrophied nucleus of the invaded cell. The 

 majority of these large cysts are situated at the base of a villus, 

 but occasionally some may be seen (generally singly) nearer the 

 apex, situated always at one side of the villus, xlssuming that 

 these represent greatly hypertrophied body cells the indications 

 are that they are epithelial in type. 



The smaller "cysts" (Lt/mjjhoci/stis mfocropodis) are situated under- 

 neath the basement membrane of the mucosa, and are definitely 

 formed within invaded cells, probably mononuclear lymph cells. The 

 cell-nucleus, even in the very early stages, when the parasite consists 

 of but foursjnall nuclei surrounded by a faintly staining spherical 

 mass of protoplasm, is distinctly pushed to the side of the cell, and 

 becomes hypertrophied as the cell increases in size owing to the 

 growth of the parasite, ultimately becoming saucer-shaped, 

 clasping the periphery of the cell. The nuclei of the parasite 

 multiply greatly, do not become regularly arranged, and finally 

 form falciform spores, which escape from the mature cyst into 

 the lumen of the intestine on the one hand, and into the lymph 

 stream on the other, as a result of which they may be found in 

 adjacent lymph glands. 



3. In the wombat {Ileocystis n-ombati) the cysts are arranged 

 around the periphery of the villi, and withiii the glands of Lieber- 

 kiihn. They are present in enormous numbers, and induce a papil- 

 lomatous condition of tlie mucosa similar to severe coccidial infec- 

 tion. The majority of the glands are completely obliterated by the 

 infection and by the tissue reaction, while the villi are enor- 

 mously hypertrophied. Many of the smaller cysts appear to be 

 degenerating, and these show a definite envelope, frequently 

 containing an enlarged cell nucleus, with single spherical nuc- 

 leolus. The living cysts are usually much larger, have a thin 

 envelope, with seldom any definite nuclear body, and an endo- 

 plasm containing in the early stages irregularly-distributed 

 minute nuclei, which, as the parasite develops, become arranged 



