136 SPOROZOA. 



and multipKcation forms also present. Cysts 12-15 /i in length 

 and 12-14 ft in width. Number of merozoites in each cyst 

 4 to 8 macro- or 12 to 24 microgametes. 



Habitat. — Blood of the tortoise, Testudo emys Schleg. & Miill. : 

 India (exact locahty not cited). 



€2. Haemogregarina thomsoni Minchin. (Fig. 61.) 



^Heemogregarina thomsoni, Minchin, 1907, pp. 1098-1104, pis. Iv-lvi, 



figs. 1-23. 

 Heetnogregarina sp., Shortt, 1917, pp. 402-8, pi. xxx, figs. 1-21. 

 Heemogregqrina thomsoni, Castellani & Chalmers, 1919, p. 487 ; 



Wenyon, 1926, p. 1388. 



Both intra-corpuscular and free forms (so-called vermicules) 

 are met with. Intra-corpuscular parasite always distinctly 

 sausage-shaped, and slightly bowed in the plane of the corpuscle, 

 this normal ciu-vature being due to the parasite being situated to 

 the side of the corpuscular nucleus. In a few cases the curve 

 of the parasite is reversed, its convexity being towards the 

 corpuscular nucleus, which is then much more displaced, and 

 the parasite resembles its free form very closely. 



Young intra-corpuscular forms vsiTy in length from about 

 a half to two-thirds of the blood- corpuscle ; cytoplasm 

 very clear, and a dehcate nucleus, consisting of faintly 

 staining granules and strands of chromatin, forms a band 

 round the waist of the parasite. Full-grown intra-cor- 

 puscular parasites are at least three -fourths the length 

 of the blood-corpuscle ; cytoplasm finely granular, nucleus 

 exceedingly rich in chromatin, forming a deeply staining mass 

 of irregularly spongy texture, occupying the middle region of 

 the body for its whole width and nearly one-third of its length. 

 The free vermicules closely resemble the full-grown intra- 

 corpuscular forms, long, medium, and stumpy forms being 

 distinguishable . 



Sometimes most of the intra-corpuscular parasites have the 

 form of an elongated sausage, slender and drawn out ; cyto- 

 plasm clear and free from coarse granulations ; nucleus forming 

 a band or zone at the middle of the body, equal in width to 

 nearly half the length of the body, and with chromatin arranged 

 in the form of transverse strands. 



Small forms are generally situated at one end of the erythro- 

 cyte ; larger forms He in the long axis of the host-ceU, and displace 

 the nucleus laterally. The parasite is usually situated with its 

 concave border embracing the convexity of the erythrocyte 

 nucleus, but its position may be reversed. Invasion by two 

 or more forms is not uncommon, the parasites lying parallel 

 to one another and both on the same side, or the two embracing 



