z6 4 
2. Hg. gerbilli. — In the red cells of Gerbillus 
indicus , an Indian field rat. Parasites are generally 
numerous. It is non-pathogenic. Two forms occur. 
(i) Endoglobular. —They lie in sharply defined oval 
cavities limited by a £ cytocyst,’ probably derived from 
the red cell. The parasite possesses a short tail sharply 
flexed upon the body. In stained specimens a nucleus 
is visible just before the bend of the tail. The tail 
portion stains deeper than the rest of the parasite and 
contains a number of chromatin granules. The red 
cells are anaemic and enlarged, and become oval, 
corresponding to the shape of the parasite. 
(ii) Vermicules .—These are best seen in blood 
that has been kept moist for some time. They 
resemble the encysted forms except that now the tail 
is straightened out (Fig. 79). 
3. Hg. canis. —Occurring in the polynuclear 
leucocytes of dogs, especially puppies, in India and 
Assam. They are about 12 by 6/^, and occur in 
a capsule or cytocyst derived from the leucocyte. The 
nucleus is generally situated at one end, and is round 
or oval (Fig. 80). 
Development. —One of us (S. R. C.) has traced the 
development of this parasite in the gut of Eu. san¬ 
guineus , the Indian dog tick. 
(i) The parasites become free, and become vermi¬ 
cular in shape. 
(ii) The vermicule enters a cell of the gut and pro¬ 
ceeds to divide, giving rise to a slender and stout form. 
(iii) Conjugation of these takes place, resulting in 
a zygote. 
(iv) These grow in size and eventually in them 
develop sausage-shaped sporozoits. 
(v) How these get out of the tick and infect dogs 
is unknown. 
