74 
Equine Piroplmmosis 
in Horses I, II and III appeared with the onset of fever ; their number 
rose and fell with the body-temperature as will be seen by reference 
to the charts given in the Appendix. 
TliC types of parasites encountered in the blood. 
Owing to the changes of form observed by us in living parasites we 
have not attached much importance to the different shapes seen in 
parasites which liave been fixed and stained. Naturally, they may 
assume a great variety of forms in death, these forms corresponding 
to what has been described in the living parasite. Enumerations of 
parasites according to their relative size lead us to no definite conclusions 
with regard to the relative prevalence of small, medium or large 
parasites at any stage of the disease. In Horse I the medium and 
large-sized parasites predominated over the small until the day of 
death, when there was an increase in small parasites ; in Horse II the 
large parasites predominated more or less considerably over the small 
forms in 15 out of 19 counts, and there was no increase of small forms 
toward death’. About 90“/o of the infected corpuscles contained single 
parasites of all shapes and sizes, usually 2-5 “/o contained 2 to 4 
parasites and 1-5 “/o contained dividing or cross-formsl Whereas in 
Horse III only few free parasites were usually encountered (0'2 to 6 Yo)> 
in Horse I as many as 26 7o of free parasites were encountered on the 
day of death, thus indicating that tlie corpuscles were rapidly breaking 
up and liberating the contained parasites’. 
These enumerations of the different types of para.sites encountered 
in the blood offer a marked contrast to what is observable in Piroplasma 
(see p. 81). 
The accompanying Diagram VI represents what appears to be the 
usual mode of multiplication of iY. equi in the circulating blood, 
judging from the observations made in the first instance upon living 
parasites, and in the second upon stained specimens. The reader is 
referred to Plate III and its accompanying description for further 
details. 
1 In this connection it .should be noted that Horse III had haemoglobinuria and 
jaundice but died without marked lesions, whereas the contrary was the case in 
Horse I. The latter’s spleen weighed 7J- lbs., the liver 12| lbs., and extensive abdominal 
haemorrhage was detected at autopsy. 
- In films from South Africa and Italy kindly lent us by Sir John McFadyean and b}' 
Professor A. Negri (Pavia) respectively, the dividing or cross-forms represented 7‘2 ®/o 
4-4 7o of the N. equi present in blood-films. 
