COCCIDIA 75 



growth, while the other developmental stages occur in the epithelial 

 cells. 



Old healed-up scars "are also very instructive. The most striking 

 appearance is the extreme proliferation of the connective tissue, by 

 which the tumour contents have become destroyed. As in the case 

 of other old parasitic foci which have become destroyed by encysting 

 with connective tissue, calcification ensues. The only remaining 

 traces of the parasitic invasion are the shells of dead oocysts. 



The same species of Coccidium is met with in the small intestine 

 of the rabbit, where it is likewise parasitic in the epithelial cells, 

 and gives rise to violent diarrhoea. Diarrhoaa, in combination with 

 emaciation and loss of appetite, is very suggestive of coccidial infec- 

 tion, the presence of oocysts in the faeces establishing the diagnosis. 

 Eimeria stiedce is found not only in the rabbit, but also occasionally 

 in man, as well as in different domestic animals (cattle, horses, goats, 

 swine). In cattle, it usually inhabits the large intestine and the 

 rectum, and gives rise to a disease known as red flux. The condition 

 is accompanied by blood in the faeces, and it appears enzootically in 

 the summer and autumn among cattle on high-lying pastures in 

 Switzerland. 



A similar parasite, E. falciformis (Eim.) which, like E. stiedce, 

 forms only a small number of merozoites, is parasitic in the house- 

 mouse. It is generally found in the intestine, more rarely in the 

 liver. 



Another Coccidium, Isospora bigemina (Stiles) is found in the 

 intestine of cats and dogs. The oocyst of this parasite contain, not, 

 as in Eimeria, four sporocysts with two sporozoites each, but two 

 sporocysts with four sporozoites each. 



(d) Pseudo-coccidiida. 



Before leaving the subject of the Coccidia, it is necessary to 

 issue a note of warning to the student as to the caution with which 

 his investigations must be pursued, for there is no class of the 

 Protozoa in connection with which mistakes are so likely to arise. 

 It frequently happened, formerly, that stages of Coccides were mis- 

 taken for the eggs of Helminthes. Now, however, that the parasitic 

 Protozoa are receiving so large a measure of attention, the tendency 

 is to discover Coccides where none are present. Eggs of Nematodes 

 and of Distoma have frequently been mistaken for Coccidia, the 

 commonest errors being in the case of Distoma turgidum, which forms 

 tumour-like swellings at the pylorus of the frog, and D. pellucidum, 

 which is occasionally found in the albumen of hens' eggs. Even the 

 calcified body of a Cysticercus has recently been mistaken for a 



