82 
Eq uine Pi) 'oplas)) i os is 
Observations on the blood. 
In the case of P. caballi Horse III (refer to protocol and chart 
in the Appendix, p. 92) there was a relatively slight decrease in the 
number of red blood corpuscles (from about 6^ to about 5 millions) and 
a slight fall in the amount of haemoglobin. The leucocytes showed a 
decided decrease as the disease advanced, accompanied by a disap¬ 
pearance of the eosinophiles and an increase in the neutrophiles. 
III. Immunity test with regard to N. equi and P. caballi. 
As a final proof of the difference between the two parasites, we 
decided to test if an animal which had recovered from the symptoms 
of “ biliary fever ” produced by the one would prove immune to infection 
with the other parasite. 
A horse inoculated with P. caballi on 22. vi. 1910 suffered from a 
mild infection, and to all outward appearances made a good recovery. 
On 2. viti. 1910^ this horse was inoculated with N. equi with the result 
that it died of “ biliary fever ” induced by this parasite 20 days later. 
Only N. equi could be found in this horse’s blood, although it might 
have been expected that P. . caballi would have reappeared. This 
was the only one of our six horses which had haemoglobinuria, and it is 
possible that the mixed infection which existed was responsible for this 
symptom. It is desirable to determine if haemoglobinuria occurs in 
a pure N. equi infection; it probably does, since the animals may show 
jaundice, but there may be a difference in respect to the frequency and 
severity of this symptom. 
It would be of considerable interest to determine if trypanblue 
affects P. caballi in a similar manner to P. canis and P. bovis" as one of 
us has shown elsewhere. The dye may, moreover, be found to influence 
N. equi differently to P. caballi. We have been unable to investigate 
this problem owing to lack of means with which to continue the 
researchI 
We have pleasure in acknowledging the kind assistance given to us 
1 Forty-two days after it had been inoculated with F. caballi. 
- Vide Nuttall and Hadwen, Parasitology, ii. 156-191, 229-235, 236-266 and Nuttall, 
Ibid. II. 409-434 and in. 202-209. 
® Note whilst going through the 'press: Dr Yakimoff, February, 1912, in a letter to one 
of us, states that Bielitzer has recently treated equine piroplasmosis successfully in Eussia 
by means of trypanblue, following the suggestion of Nuttall and Hadwen. This dye has 
now been found of value in the treatment of canine, bovine and equine piroplasmosis. 
