764 



THE COCCIDIA 



The microgamete bears a considerable resemblance to the spermatozoa of higher 

 animals : it is very small (6-8/x long), actively motile, generally falciform, with an 

 homogeneous refractile body, and is almost entirely composed of chromatin surrounded 

 by a very thin layer of protoplasm (fig. 366). 



3. Fertilization. The mature macrogamete attracts the microgametes by chemio- 

 tactic influences : a single microgamete penetrates the female cell at the micropyle 

 and as soon as it has passed into the macrogamete the micropyle closes behind it. 

 The male element reaches the nucleus of the macrogamete and fuses with it, forming 



FIG. 366. Free microgametes of Echinospora. 

 (After Leger.) 



FIG. 367. Fertilization in Coccldium schubergi. 

 (After Schaudinn.) 



the oocyst, and fertilization is now completed. 1 The oocyst then leaves the body 

 of its host, matures, and divides by sporogony, giving rise to sporocysts, which will 

 infect new hosts (vide ante). 2 



Other principal species of coccidia. 



The genus Coccidium comprises about forty species which are parasitic in 

 the mammalia, birds, reptiles, batrachians, fish, myriapods and insects. The 

 following species may be mentioned in addition to those already noticed : 



Coccidium falciforme, a parasite of Mus musculus ; C. avium (vel C. tenellum), 

 a parasite infecting fowls, pheasants, etc. ; C. salamandrce ; C. pfeifferi, a 

 parasite of doves ; C. jalinum, observed by Perron9ito, Dematteis and Borini 

 in a case of chronic enteritis. 



According to Wasiliewski, C. bigeminum (vel Cystospermium villorum intestinalium 

 canis) which has its habitat in the villi of the intestine of dogs and cats, is probably 

 the same parasite as that found by Kjellberg hi Berlin in the intestinal villi of a 

 man, and should be classified with the Diplospora, a genus closely related to the 

 Coccidia and characterized by the fact that the oocyst produces two sporocysts each 

 giving origin to four sporozoi'tes. 



The genus Eimeria (Schaudinn), in which Blanchard includes the parasite found 

 by Kiinstler and Pitres in a case of pleurisy in man (E. hominis), should apparently 

 be classed among the Coccidia. 



Unclassified Coccidia. Kartulis has recorded cases in which Coccidia were the 

 cause of tumours in muscles. Londermann found brownish-looking tubercles, 

 2-3 mm. in diameter, and containing coccidia, in the sigmoid valves of the aorta 



1 The fertilized cell is sometimes known as the zygote. 



2 In some species, the oocyst matures in the tissues of the infected host and may at 

 once infect new hosts without passing through an extra-cellular stage. These coccidia 

 are directly contagious (C. truncatum of the goose ; C. proprium of the triton). 



