ISOSPORA. 163 



harbour three distinct species. One, or probably two, species 

 are known from man. Becker (1934) gives the names and 

 hosts of 42 named species and the hosts of 4 unnamed species 

 oi Isospora. 



Key to Indian Species. 



1 (12). Infection limited to epithelial cells. .. 2. 



2 (4). Oocysts spherical 3. 



3. Oocysts 18-23|u, in diameter; sporo- 



cysts 12-15 fj. by 8-10 /u.. Intra- [Das-Gupta, p. 170. 



nuclear /. knowlesi Ray & 



4 (2). Oocysts not spherical 5. 



5 (10). Oocysts egg-shaped 6-9. 



6. Oocysts 25-33 ;u by 12-5-16 ^u ; sporo- 



cysts 12-14 ;u. by 7-9 ^i. In man ... /. belli Wenyon, p. 163. 



7. Oocysts 35-45 /x by 25-35 ;li; sporo- 



cysts 18-4 fi by 11-4 jLt. In cats ... J./eZ^s Wenyon, p 168. 



8. Measurements of oocysts and sporo- [p. 167. 



cysts not recorded. In lizards .... /. calotesi, sp. nov., 



9. Oocysts 15;u..by 1-5 jx; sporocysts [Das-Gupta, p. 170. 



7'5 |Lt in diameter. In cobra /. minuta Mitra & 



10 (5). Oocysts subcylindrical 11. 



11. Oocysts 16-20 /x by ll-14ju.; sporo- [Das-Gupta, p. 172. 



cysts 8 ;u. by 4 ju. /. wenyoni Ray & 



12 (1). Infection may extend to the sub- 



epithelial tissue also 13. 



13 (14). Larger oocysts 18-20 /x by 14-16 ;Lt (in 



dogs); smaller oocysts 10-14 /x by 



7-5-9 yu, (in cats and dogs); sporo- [p. 165. 



cysts 13-5-15-5/x by 9-10 /x /. higemina (Stiles), 



14(13). Oocysts 20-25 /x by 15-22 /lx; sporo- ' [p. 171. 



cysts 16 /L4 by 10/x , . . . /. rivclta (Grassi), 



95. Isospora belli Wenyon. (Fig. 74.) 



Isospora liojninis, Dobell, 1922, pp. 1497-8, fig. 533 A. 

 Isospora belli, Wenyon, 1923 a, p. 269. 

 'fisospora belli, Knowles, 1924, p. 64. 

 Isospora belli, Wenyon, 1926, pp. 820-4 fig. 350, 7-10; 1926 a, 



pp. 253-66. 

 Isospora hominis, Dobell, 1926, pp. 74-85 ; Craig, 1926, pp. 349-53, 

 fig. 62. 

 '\Isospora belli, Knowles, 1928, pp. 356-8, fig. 81, 4, 17-21. 

 Isospora belli, Reichenow, 1929, p. 958, fig. 923 ; Kudo, 1931, 



p. 274, fig. 114, a-c ; Calkins, 1933, p. 405. 

 jlsospora belli, Knowles, 1933, p. 53 ; Das-Gupta, 1934, pp. 133-4, 

 pi. ii. 



Only the oocysts and sporocysts are known. The former 

 are elongate, egg-shaped, with one end more constricted 

 than the other, forming a kind of neck. They are transparent, 

 colourless bodies, with a wall consisting of two layers, the outer 

 thick and porcellanous, the inner thin and membranous. 

 At the narrow end there is an indication of a micropyle. 

 In fresh stools are found unripe oocysts with cytoplasmic 



m2 



