146 



THE ANIMAL PARASITES OF MAN 



more confined space in which they are formed. Formerly, the para- 

 sites in the liver were described under the name of Coccidinm oviforme, 

 while those from the intestine were termed Coccidinm perforans. This 

 distinction has now broken down. 



The oocysts 1 are thick-walled, somewhat flattened at one pole, 

 where a large micropyle is present. Four egg-shaped spores (sporo- 

 cysts) are formed within, each about 12 //, to 15 //, long and 7 p broad 



FIG. 71. Eimeria stied<z t from 

 the liver of the rabbit, oocysts 

 in various stages of development. 

 (After Leuckart.) 



FIG. 72. a, b, spores of 

 Eimeria stieda (Riv.), with 

 two sporozoites and residual 

 bodies ; c represents a free 

 sporozoite. (After Balbiani.) 



(fig. 72). The oocysts are voided with the faeces. Sporogony takes, 

 in nature, about three days in the excrement. Faecal contamination 

 of the food of rabbits results, and coccidian oocysts are swallowed. 

 Under the influence of the pancreatic juice of a new host, the 

 sporozoites (fig. 72, a c) are liberated from the spores and proceed 

 to attack the epithelium and multiply within it, as in the case of 



Eimeria avium. From the gut, 

 infection spreads to the liver, 

 where multiplication of the para- 

 site goes on actively, resulting 

 in the formation of the whitish 

 coccidial nodules, which may be 

 very conspicuous (fig. 74). Pro- 

 liferation of the connective tissue 

 may occur around the coccidial 

 nodules, which then contain large 

 numbers of oocysts in various 



stages of development. It is said that the oocysts in the older nodules 

 do not seem to be capable of further development. Schizogony (fig. 73) 

 and gametogony in all stages can be found in both liver and gut. 



FIG. 73. So-called swarm cysts (endogenous 

 sporulation or schizogony) of the Coccidium of 

 the rabbit. The daughter forms are called 

 .merozoites. (After R. Pfeiffer.) 



1 For an account of the life-cycle of Eimeria stiedce consult Wasielewski, Th. von (1904), 

 "Studien und Photogramme zur Kenntnis der pathogenen Protozoen," Heft. I (Coccidia), 

 118 pp., 7 plates, Leipzig: J. A. Earth. Also, Metzner, R. (1903), Arch. f. Frotistenk., ii, p. 13. 



