788 THE INTRA-CORPUSCULAR ILEMATOZOA 



2. Pyriform parasites measuring 2 '5-3 '5^ long and occurring in pairs, the 

 narrow end of each being continuous with or contiguous to the tapering end 

 of the other hence the name bigeminum. Sometimes two entirely separate 

 pyriform parasites are seen, in which case the pointed ends are often turned 

 away from each other. In stained preparations two masses of chromatin 



FIG. 381. Piroplasma bigeminum. Blood from a cow. x 1000. 



can be seen in the larger end of the pear-shaped parasite a rounded or oval 

 nucleus and a blepharoplast and the pointed end often shows scattered 

 granules of chromatin. 



In some of the free forms the pointed end of the parasite is prolonged into 

 a pseudo-flagellum terminating in a point and staining with difficulty (Lig- 

 nieres, Fantham). 



In the blood of the peripheral circulation the pyriform bodies are much 

 more numerous than the round or oval forms. They represent sexual sporonts, 

 development taking place in the stomachs of ticks (Doflein and Liihe). 



In the blood, these pyriform parasites multiply asexually by longitudinal 

 division, the chromatin dividing first : the infected red cell then contains 

 two parasites : occasionally these two parasites divide again and the red 

 cell then contains four pyriform parasites. The occurrence of four parasites 

 in one cell may also be accounted for by supposing that it was originally 

 infected with two parasites. 



[Nuttall and Graham-Smith 1 from a prolonged study of the living parasite 

 of canine piroplasmosis and a comparative study of stained films of P. canis, 

 P. bigeminum (P. bovis) and P. pithed have established the fact that these 

 three species multiply in precisely the same manner, namely by a peculiar 

 process of budding by which a single amoeboid body usually gives rise to two 

 pyriform parasites. 



[A free pyriform parasite enters a normal red blood corpuscle and after a 

 time assumes a rounded form, grows, and becomes actively amoeboid. The 

 amoeboid parasite then protrudes two symmetrical bud-like processes, which 

 rapidly grow and become pear-shaped ; the protoplasm of the parasite 

 flows into these " buds " and the body consequently becomes smaller until 

 it is represented by a minute mass to which the pyriform bodies are attached. 

 This minute mass ultimately disappears and two mature pyriform parasites 

 are left, joined for a time by a filament which finally ruptures leaving them 

 free. After a variable length of time the parasites escape from the corpuscles 



1 Journal of Hygiene IV., V., VI., VII., and Parasitology I. 



