Ill 



CHAPTER VIII. 



PIROPLASMOSIS. 



Piroplasmosis. " Malaria " of cattle, horses, dogs, &c. 

 Piroplasmosis is the term sometimes applied to the affec- 

 tion caused by certain sporozoal blood parasites (Plate II, 

 24-27) which, being commonly pear-shaped, are called 

 piroplasmata. The piroplasmata differ from the haem- 

 amcebas in that (i) they do not form pigment ; (2) division 

 is usually into two, sometimes into four, and the young 

 forms are not immediately set free, but continue to grow 

 in the red corpuscle in which they live. Ultimately they 

 escape from these red corpuscles. It is probable that a 

 large proportion of their nutriment is derived by osmosis 

 from the blood plasma and less from the haemoglobin than 

 in the haemamcebae. The free parasites may be found in 

 the plasma, actively motile, before they enter other cor- 

 puscles ; (3) they are conveyed in all known instances by 

 ticks of various genera. The diseases are transmitted not 

 by the tick that feeds on the infected animal, but by the 

 second and sometimes the third generation of these ticks, 

 as the parasites are transmitted to the eggs and develop 

 in the young ticks. 



The piroplasmata in the early stage have no definite 

 vesicular nucleus, though a clear non-stained space 

 or vacuole is present. The chromatin is frequently in 

 two equal or unequal masses, and though it divides to 

 some extent the complete fragmentation and diffusion 

 observed in the malarial parasite does not occur. 



Division is more by a process of budding than of 

 breaking up into spores. The pear-shaped body, after 

 escaping from a red corpuscle, enters another and then 

 becomes a rounded amoeboid mass. In this stage it does 

 not escape from the red corpuscle. After a time two 



