388 ALDO GCASTELLANI AND ARTHUR WILLEY. 
genus of Hemamebide. Weaccordingly named it Hamo- 
cystidium simondi.! No Hemogregarine forms were 
found accompanying it. At the earliest stage observed it 
consists of a small irregular body with a belt of pigment 
granules across the centre, occasioning a slight displacement 
of the nucleus of the corpuscle. 
With increase of size of the parasite the nucleus of the 
host-cell becomes pushed to one end of the corpuscle (PI. 
24, fig. 4). 
The parasite was not observed in the fresh state, but in 
preparations stained by Leishmann’s modification of Roma- 
novsky’s method two distinct kinds are found, resembling one 
another in size and form, but differing in their reactions to 
the stain. 
These, no doubt, represent sexual differences, as in Halte- 
ridium. In the male type the body is seen to be faintly 
granular, the protoplasm is stained a delicate pale-blue, with 
numerous small pigment granules scattered round the peri- 
phery and in the substance of the oval or discoidal organism. 
In the female type the body is stained dark-blue, and the 
pigment granules are numerous, though appearing on the 
whole rather larger than in the male trophozoite. The 
female trophozoite differs further from the male by the 
constant presence of vacuoles, varying in number and size 
(Pl. 24, fig. 4). 
Sometimes the contour of the He mocystidium makes an 
almost perfect circle, and in accordance with the shape of the 
blood-corpuscle it is probable that the parasite is not spheri- 
cal but rather shaped like a biconvex lens. Its diameter 
nearly equals the shorter diameter of the corpuscle, while the 
elongated forms nearly fill the latter. 
In one case of a double infection the growth of the two 
male trophozoites had caused a deep constriction of the 
blood-corpuscle, nearly cutting it in two. 
The species described by Dr. Simond, which should now be 
1 Castellani and Willey, in ‘ Spolia Zeylanica,’ vol. ii, 1904, p. 84. 
