G. H. F. Nuttall and G. S. Graham-Smith 139 
taken at a period of very active multiplication, for typical dividing forms 
were found in almost every field 1 . 
We have figured a selected series in Diagram II, which may be 
compared with our schematic figure of the usual mode of multiplication 
in P. canis which we have reproduced (Diagram I). 
P. pitheci, P. H. Ross, 1905. 
This parasite was discovered by Dr Philip H. Ross in the blood and 
internal organs of a species of Cer copith ecus, and was described by him in 
the Journal of Hygiene, I. 1905, v. pp. 18—23. As he did not illustrate 
the parasite the true nature of the organism still remained in doubt. 
Through the kindness of Dr Ross we have had the opportunity of 
studying his slides. One blood film contained only a single parasite, 
but another contained over one hundred. A smear preparation from 
the liver contained large numbers of parasites but was not as well fixed 
or stained as the blood preparations. All these preparations were 
systematically examined and the parasites sketched 2 . 
These observations have convinced us that the parasite described by 
Ross is a true Piroplasma, and multiplies in the same manner as 
P. canis and P. bovis. 
The number of parasites contained in infected corpuscles varied from 
1 to 16. 
1 
2 
3 
4 
5 
6 
8 
10 
.Number of parasites per infected corpuscle 
In blood films 
In liver smear 
Common 
Common. 
One found 
Found 7 times 
Not found 
None found. 
Fairly common. 
Not found. 
>> 
Found 6 times 
Not found 
»» 
Fairly common. 
Two found. 
The prevalence of the paired forms and the occurrence of the usual 
multiples 2, 4, 8, 16, accord with what we have observed in P. canis. 
1 Of 500 consecutive infected corpuscles examined 55 % contained single parasites, 
34 °/ 0 double parasites and 11% contained parasites in the typical process of division. 
We would particularly emphasize the fact that numerous dividing forms are only to be 
occasionally met with, consequently negative results, on the examination of single films, 
or even a series of films from a single animal, cannot be accepted as evidence against this 
beiug the usual mode of division. 
2 Our thanks are due to Mr C. Strickland, who searched through the second blood 
preparation with great care. 
