G-. H. F. Nuttall and S. Had wen 
163 
It is a significant fact that the highest percentages of parasites 
belonging under categories (PPPP), (D), (P) and (00) were counted 
only in the cases of dogs which died of piroplasmosis. Thus, in Dog 
10, a small puppy, there were counted at various times as many as 
10°/ 0 (PPPP), 7% (D), 6°/ 0 (P) and i°/ 0 (00) at an early stage of the 
disease. In Dog 11 there were, on one occasion, as many as 13% 
(PPPP) present, whilst in Dog 2 there were no less than 20% (PPPP) 
present on the day the animal died. In any case, the percentages above 
quoted sufficiently prove that the commonest forms of parasites are the 
(0) and (PP) forms. If the actual number of parasites in a corpuscle 
were enumerated it naturally follows that the percentage for (PP) parasites 
would be doubled, for each “ P ” represents an independent parasite. 
In connection with our studies upon the effects of drugs upon 
P. cams we found it necessary to make very careful examinations of 
the blood both in our control dogs and in those that were treated. 
This led us to examine the peripheral blood for the earliest appearance 
of parasites, and, as the disease progressed, to record the percentage of 
infected to uninfected corpuscles. 
At first very few corpuscles are found to harbour parasites, and they 
can only be found with difficulty along the edge of the film , or at the 
end of the film, in the region where the leucocytes are encountered in 
greatest numbers. At this stage many thousands of uninfected corpuscles 
occupy the greater part of the film, and it is practically impossible to 
estimate the percentage of infected corpuscles. We have been satisfied 
in such cases to note the presence of parasites “ only at film-edge.” 
As the disease advances the percentage of infected corpuscles usually 
rises steadily until it attains its maximum shortly before death (30 to 
80% or more). When the disease runs a more chronic course there 
maybe fluctuations in the percentage of infected to uninfected corpuscles. 
The effects of Trypanblau and Trypanrot upon the 
morphology of Piroplasma eanis. 
The effect of Trypanblau and Trypanrot upon the morphology of 
P. cams is exceedingly striking. The pyriform parasites rapidly dis¬ 
appear and the proportion of rounded parasites is increased so that after 
a time all the intracorpuscular parasites appear rounded. Moreover, 
some of the parasites, when viewed in stained preparations, show visible 
signs of degeneration in that they may present a ragged or irregular 
11—2 
