KEl’OKT OF TKAVEbLING FATHOLOGIST AND I’KOTOZOObOUIST 
155 
in the same situation, but also are able to attack the red blood-corpuscles. It has been stated 
uniformity in size is a feature of the intra-corpuscular forms, so that it cannot be assumed that 
they seek this situation for trophic reasons. It is possible that the forms in the blood are 
undifferentiated gametes, the end-product of a special sporogony iu the liver, and that the 
larger forms really represent the asexual forms, which continue multiplying in the liver by 
schizogony. 
In this connection it is interesting to recall the somewhat similar conditions of multiplica¬ 
tion which are found in the life-history of Ilcemogregarina halfoari of the jerboa. If the figures 
of the hiemogregarine at present under consideration (Plate XII.) he compared with the 
figures given by Balfour in his account of the haemogregarine of the jerboa (Plate XII., Second 
Eeport, Wellcome Eesearch Laboratories), the similarity will be at once evident. The differen¬ 
tiation into micro- and macro-merozoites is not so marked as in the lizard parasite, but it is still 
quite definite. There is the oval-contoured schizont which gives rise to three or four sausage¬ 
shaped bodies (in the lizard the number of these bodies is larger), while the spherical schizonts 
give rise to a number of small merozoites. Balfour seems to say that the oval schizont breaks 
up into the sausage-shaped bodies, each of which then grows into the large schizont which 
gives rise to the small merozoites which appear in the blood. A small merozoite from the 
blood is then supposed to attack a liver-cell and commence the cycle again by giving rise to 
the oval schizont. If this were the case, one would expect to find several of the spherical 
schizonts developing at one spot, as it can hardly be supposed that ihe sausage-shaped bodies 
would separate before growing into schizonts. 
In both cases it seems more probable that the two processes are independent of each 
other in so far as they do not represent part of one continuous cycle. There is probably a 
division or schizogony into macromerozoites and a schizogony into micronierozoites in exactly 
the same way as occurs in many Coccidia, in which case we must allow that only the 
micromei’ozoites gain access to the blood, or that there is an asexual cycle confined to the 
liver (the oval schizonts and sausage-shaped bodies of the two h®mogregarines) and a sexual 
cycle which gives rise to undifferentiated gametes, the sporogony taking place in the liver also, 
but the gametes taking up their position iu the red blood-corpuscles. The continuation of the 
development might then be a conjugation of the gametes in some intermediate host. 
According to this latter view, there is a close similarity between this development and the 
life-cycle of the Schizogregarinoe as described by L6ger and others. Association into pairs 
of the haemogregarines of other animals has been described, both in the red-blooded host and 
also in the blood-sucking host. If this view holds good, the haemogregarines of the blood 
would be the undifferentiated gametes or sporoblasts; but until something further is known 
of the life-cycles no definite conclusion can be arrived at. 
For this haemogregarine of the lizard, Mabuia quinquetceniata, I propose the name 
llcemotjregarina gracilis, on account of its narrow body and delicate structure. 
Comparison 
with 
hcemogre- 
garine of 
jerboa 
An asexual 
and a sexual 
cycle 
HjiirOGKEGARINES 
Parasites belonging to this genus were discovered in a number of snakes and other 
animals. They will be referred to below under the names of their respective hosts. 
1. Naja hajes (Plate XIV., figs. 8, 12, 18-20, 22-24) ; Naja nigricollis (Plate XV., 
figs. 3, 4, 8). 
Locality, Eiver Sobat 
This hmmogregarine occurs with a trypanosome and haemocystidium in the blood of the 
spitting cobra. There are several distinct types of this hoemogregarine. (a) Looped form 
within cyst, staining a deep blue ; nucleus round and compact; protoplasm free from granules; 
