H.SiMOGREGAIUNE OF THE JEKHOA 
35 
which ajjpears to retain its characteristic size and shape throughout the illness it induces. 
At the same time, I admit that the last word has not been said about this trypanosome either, 
and it is a pity that the laboratory strain obtained from Dr. Wenyon was lost at the time 
of the fire, as one had hoped to reach some definite conclusion regarding it. Doubtless, 
however, we will in time arrive at a correct understanding regarding all the different species 
found in the Sudan, and, for the present, Plate I., on which are grouped all those hitherto 
found, should materially aid those engaged in blood examinations and veterinary work. 
According 
II .l<:MOOnEGAlUNE OF THE JeUISOA 
By the Dikectok 
Ilaimogregarina jac.uli (Balfour) 
to the laws of nomenclature the above must be the name of the 
h^mogregarine of jerboas described in the Second Eeport, and not //. halfouri (Laveran) as 
there stated. Further observations have been made on this parasite, but all efforts to find 
an extra-corporeal stage in an insect host have met with failure. In the first place, 
however, one may consider the blood conditions. In the case of other haemogregarines of 
mammals, notably H. gerhilli (Christophers) and II. funamlmli (Patton), careful differential 
leucocyte counts have been made of the blood of infected and of non-infected animals. 
The discovery of uninfected jerboas (J. gordoni) enabled me to institute similar comparisons 
in the case of these rodents. 
In a jerboa with a large infection, I found the following percentages:— 
Polymorphonuclears ... ... ... ... ... 40-4 
Large monomrclears ... ... ... ... ... 57-8 
Small mononuclears ... .. ... ... ... 1-4 
Basophiles 
0-4 
with a very slight infection, where, after prolonged 
a large film, the percentage count was : — 
search, only 
Polymorphonuclears... 
()2-2 
Large mononuclears... 
34-4 
Small mononuclears... 
0-0 
Basophiles 
in an uninfected jerboa, the percentages were :— 
3-4 
Polymorphonuclears ... 
39-(; 
Large mononuclears 
58.() 
Small mononuclears 
()-0 
Basophiles 
1-8 
In each instance 500 cells were counted. From these and other observations it would 
seem that infection does not markedly alter the differential leucocyte count. Observations 
have been made on foetal and newly-born jerboas, the progeny of infected mothers. These 
have invariably been found free from infection. 
Young uninfected jerboas have been kept in the same mouse jar with their infected and 
flea-infested mother, but they did not acquire the parasite. This experiment was of nearly 
a fortnight’s duration. 
A jerboa inoculated with the blood of an infected jerboa also failed to show the 
parasite, and experiments with fleas fed on heavily infected jerboas and then transferred, 
while still gorged with blood, to uninfected jerboas, jiroved negative. 
Differential 
leucocyte 
counts 
Failure to find 
insect host 
