246 



THE TELOSPORASIDA AND THE COCCIDIA PROPER 



best to draw attention to the chicken form 

 by giving it a name of its own. Conse- 

 quently it is named Cryptosporidium 

 tyzzeri. 



In this connection, too, it might be 

 mentioned that Tyzzer (1910) was unable 

 to infect the laboratory rat with the 

 closely related C. niuris from the labor- 

 atory mouse. 



CRYPTOSPORIDIUM MELEAGRIDIS 

 SLAVIN, 1955 



Pathogenesis : According to Slavin 

 (1955), C. »ieleagridis may cause illness 

 with diarrhea and a low death rate in 10- 

 to 14 -day-old turkey poults. 



CRYPTOSPORIDIUM SP. 



Tyzzer (1929) remarked in passing 

 that he had found a Cryptosporidium 

 morphologically similar to C. parviim in 

 the rabbit's intestine, but did not discuss 

 it further. No one else appears to have 

 recognized this form. 



Host : Domestic turkey. 



Location : All stages occur on the 

 villus epithelium of the terminal third of 

 the small intestine. 



Geographic Distribution : Scotland. 



Prevalence : Unknown; found in 1 

 flock. 



Morphology : This species was des- 

 cribed by Slavin (1955). The oocysts are 

 oval, 4. 5 by 4. |i , with very foamy cyto- 

 plasm and an eccentric, faint, poorly de- 

 fined wisp of nucleus. No sporulated 

 oocysts were seen. 



Life Cycle : The young schizonts 

 (trophozoites) are attached to the epithe- 

 lium of the villi, often in enormous num- 

 bers. They have an attachment organ 

 which penetrates the striated border of 

 the epithelial cells. Slavin also saw 

 these forms in the goblet cells, between 

 cells as far down as the basement mem- 

 brane, and in surface depressions between 

 the epithelial cells. The mature schizonts 

 measure 5 by 4^ and contain 8 merozoites. 

 These are falciform, 5 by 1 ^i. , and taper 

 toward the ends, with one end blunter than 

 the other. The nucleus is subterminal. 



The microgametocytes are rounded 

 or oval, 4 fi in their greatest diameter, 

 and contain 16 intensely staining rod-like 

 microgametes. These measure 1 by 0.3 n 

 and have no flagella. The macrogametes 

 are roughly oval, 4. 5 to 5. by 3. 5 to 

 4.0ji. 



FAMILY AGGREGATIDAE 



Members of this family are hetero- 

 xenous, with two hosts. Schizogony takes 

 place in one and sporogony in the other. 

 Development takes olace in the host cell 

 proper. The oocysts typically contain 

 many sporocysts. With one dubious ex- 

 ception, the Aggregatidae are parasites of 

 marine annelids, molluscs and Crustacea. 



Genus MiROCYSTlS Dalcin, 1911 



In this genus the oocysts contain num- 

 erous sporocysts, each with 2 sporozoites. 

 A single species, M. kathae, has been 

 named. It occurs in the kidney of the 

 whelk, Buccinuni undatiim. 



In addition, Paichuk (1953) described 

 oocysts in the feces of several pigs in 

 Kazakhstan which he called Merocystis 

 sp. The oocysts are short-oval, almost 

 spherical, 34 to 43 by 30 to 37 ^t with a 

 mean of 38.7 by 33. Ojix. The oocyst wall 

 is smooth, 2y. thick, composed of 3 layers 

 of which the outer is dark brown, the mid- 

 dle bright green and the inner yellow-green 

 or bright brown. The oocyst wall is very 

 fragile. The number of sporocysts is un- 

 known, but more than 13. The sporocysts 

 are spherical, 9 to 13 /i in diameter with 

 a mean of 9. 1 jj, . The presence of an 

 oocyst polar granule is unknown. The 

 oocyst and sporocyst residua are com- 

 posed of dispersed granules. The sporo- 

 zoites are spherical, 4.3/i in diameter. 

 Altho Paichuk assigned this form to the 



