Gr. H. F. Nuttall 
303 
be found that 30 to 40 "/o contain two piriform parasites joined at their 
tapering extremities —this appearance is characteristic of wliat I regard 
as the genus Piroplasma, of which the species canis, caballi, ovis, hovis 
or higeminum, and divergens may be taken as examples. Of the 
remaining infected corpu.scles about 50-70 “/o contain single parasites of 
varying form, whilst a few (anywhere from 0‘5 to 11 "/„) show character¬ 
istic dividing forms, whose signiticance I pointed out some years ago, 
with Graham-Smith. Piroplasma canis and P. pithed differ slightly 
from other piroplasms in that some infected coipuscles (about 1-4 "/o) 
contain more than two parasites {i.e. 4-16) although in P. hovis four 
parasites ai’e occasional!}' found within a corpuscle. The usual mode of 
multiplication of Piroplasma is shown in the accompanying Hgure 
(Fig. 1). 
True piroplasmosis occurs in cattle, sheep, horses and dogs in many 
parts of the world. The parasites which cause the disease in each of 
these species of mammals are specific in respect to their pathogenic 
action: for instance, the parasite which occurs in the dog (P. canis) is 
only capable of setting up the disease in the dog. Parasites having the 
morphological characters of Piroplasma have been discovered iir the 
monkey and rat [P. pithed, P. muris), but the symptoms they produce 
and their mode of ti’ansmission are unknown. 
In the domesticated animals above enumerated, the presence of 
piroplasms in the blood is accompanied by a definite train of symptoms 
following upon the animals being attacked by pathogenic ticks. Usually 
about 8-10 days after the animals have been attacked by the ticks they 
show high fever, loss of appetite, haemoglobiuuria, icterus, and a large 
number of the animals die in a few days—anywhere from 25-100 “/o 
succumbing to the infection. The haemoglobiuuria is chiefly due to 
the destruction of the blood corpuscles by the parasites, the haemoglobin 
being eliminated from the kidneys. The urine may appear lightly 
tinged with haemoglobin or very dark, depending upon the intensity of 
the blood destruction. In severe cases, the number of corpuscles in the 
circulating blood may be reduced to a third or less, the blood, con¬ 
sequently, appearing thin and watery. When animals “ recover ” they 
do so slowly, and the parasites grow very scarce in the blood so that 
they cannot, as a rule, be detected microscopically. 
The parasites persist in the blood of “ recovered ” animals for years 
after they have, to all outward appearances, resumed a healthy condition, 
“ Recovered ” or “ salted ” animals are not susceptible to reinfection, and 
consequently possess enhanced value in countries where piroplasmosis is 
