316 Hciernogregarines 
This work was completed in 1917 in Petrograd, but could not be published 
in Russia on account of conditions that resulted from the revolution. I am 
indebted to Professor V. Dogiel for placing at my disposal this material, and 
for his assistance in the treatment of it. On my arrival in England in May 1920, 
I had to revise this paper and bring it up to date, since we were altogether 
out of touch with recent scientific literature in Russia. I avail myself of the 
opportunity to express my warmest thanks to Professor Clifford Dobell, who 
has given me valuable advice in my work and provided me with all the 
necessary literature and accommodation at the National Institute for Medical 
Research, London. I am further indebted to the Medical Research Council 
for a grant which enabled me to proceed with this work. 
1. HAEMOGREGARINES FROM SNAKES. 
Host: Bitis gabonica (labelled Snake No. 4), from Mabira, June 6th, 1914. 
The parasites are encountered within the blood corpuscles exclusively. 
The degree of infection of the latter is not great. The haemogregarine occupies 
not more than three-quarters of the length of the host-cell, which remains 
unaltered both as regards form and size. No influence of the parasite on the 
structure of the nucleus of the erythrocyte was observed; the nucleus is only 
dislocated, as is usual in haemogregarinosis. 
In form this haemogregarine resembles the generic type represented by 
Haemogregarina stepanowi from a tortoise, Emys orbicularis (Reichenow, 1910). 
The body of our form is more or less bean-shaped, one end being somewhat 
broader than the other (Plate XVIII, figs. 2, 3). The concave side of the body, 
in most cases, corresponds to the convexity of the nucleus of the erythrocyte, 
but frequently this side is turned to the periphery of the blood corpuscle. 
Minchin (1907) believes that the bean-shaped form of the intracorpuscular 
parasite is due to its adaptation to the space limited, on one hand, by the 
convexity of the nucleus of the erythrocyte and, on the other hand, by the 
curvature of the margin of the corpuscle, and explains the reverse position 
of the parasite by its active movements preceding the abandonment of the 
corpuscle. Reichenow (1910), however, disputes this point of view and holds 
that the bent form of the parasite is due, not to the influence of the nucleus 
of the host cell, but to the structure of its protoplasm. The latter opinion is 
perhaps correct, as it may be frequently observed that the nucleus of the 
erythrocyte is displaced to one of the ends of the parasite, the concavity of 
which, nevertheless, corresponds to the convexity of the host nucleus. 
The protoplasm of the haemogregarine is uniformly granulated, no special 
inclusions being visible in it. The nucleus is centrally located, occupying 
about one-quarter of the body length. The parasite is surrounded by a light 
area. The chromatin substance of the nucleus seems to be arranged in the 
shape of trabeculae or a network, and sometimes assumes the aspect of a 
glomerulus resembling a stage of division described by Prowazek (1907) in 
Haemogregarina platydactyli. Such a picture of the nucleus shows that we are 
