192 SPOKOZOA. 



and large intestine. The oocysts described by him possessed 

 a distinct micropyle. ZubHn (1908) studied the development 

 of the oocyst outside the body and also noted that although the 

 majority of oocysts were 12-15 )u. in diameter, larger forms, 

 which measured 30-35 ju, in length by 20 ft in breadth, also 

 occurred. Theobald Smith and Graybill (1918), who investi- 

 gated coccidial dysentry of calves in America, also encountered 

 oocysts of two types. The second t3^e, which evidently 

 corresponds with E. smithi, were said to be brownish in colour, 

 possessed a thick wall, and measured 25-8-41-8/x in length by 

 16-4-24-6/x in breadth. They did not contain any oocystic 

 residue, but sporocystic residue was present. 



Wenyon (1926) considered it possible that there were 

 two species of Eimeria found in cattle, but was led to identify 

 and figure the larger, oval type as E. zilrni. 



Cooper (1924) apparently was the first to record bovine 

 coccidiosis in India. He (1926 a) noted the extreme variation 

 in shape and size of the oocysts, but considered these variations 

 to be connected with the rate of multiplication. According 

 to him, in normal "carrier" infection all oocysts are weU 

 formed, with a strong, thick capsule and with a relatively 

 large amount of dense and granular protoplasm, but very large 

 and extremely small forms are encountered, and display 

 considerable range of variation in shape. At the height of 

 multipHcation oocysts are small, and they show an almost 

 uniformly ovoid to a nearly round shape, with distinctly 

 thinner capsules. When clinical symptoms occur still smaller 

 oocysts appear, usually in smaU numbers ; these have an 

 extremely thin capsule and much reduced amount of almost 

 transparent protoplasm. In discussing the pathogenicity of 

 bovine Coccidia, Cooper (1926 b) maintained that a latent or 

 " carrier " type of infection is of almost universal occurrence 

 in cattle in India, and that, although usually imiocuous, 

 the parasites are capable, under certain conditions, of over- 

 coming the animal's natural defences and then set up a cHnical 

 disease identical with what is described in other countries as 

 " red dysentery." He also observed that clinical coccidiosis 

 also occurs as a sequel to rinderpest, even a mild attack of 

 which may result in an appreciable resuscitation of Coccidia. 

 Later (1927) he again reviewed bovine coccidiosis, but the 

 possibihty of the existence of two species did not occur to him. 

 YakimofiF and Galouzo (1927) surveyed the previous htera- 

 ture on bovine Coccidia and gave a table noting the measure- 

 ments of oocysts and other character as given by previous 

 workers, and came to the conclusion that the name E. ^iirni 

 should be restricted to the forms with smaller and spherical 

 oocysts, while larger and oval oocysts should be referred to 

 a new species, E. smithi. 



