THE ILEMOSPORIDIA 



379 



The best-known member of this group of organisms is a parasite 

 of the blood of cattle (Fig. 160), which has been most unfortunate 

 in its nomenclature, and has appeared under a variety of generic 

 names (Hcematococcus, Pyrosoma, Apiosoma, Piroplasma), but of 

 which the correct name is probably Babesia bovis (or bigemina). 

 The typical form of this parasite is a pear-shaped body within the 

 blood-corpuscle. It multiplies by binary fission, and is often 

 double in consequence whence the specific name bigemina. 



Many other species are now known, parasites of domestic animals in 

 various parts of the world, and of recent years a number of species have 

 been made known from wild animals, but our knowledge of piroplasms 

 in a natural state is not very extensive. No species is known with 

 certainty to be parasitic upon human beings, but a disease known 

 as " spotted fever of the Rocky Mountains " has been stated to be 

 caused by Piroplasma hominis, and it is possible that the organisms 



FIG. 160. Piroplasma, bigeminum (Babesia bovis) in the blood-corpuscles of the 

 ox. a, b, Youngest forms ; c /, binary fission ; g j, various forms of 

 the twin parasites ; k, I, doubly-infected corpuscles. After Laveran and 

 Nicolle. 



described from the blood of yellow fever patients by Seidelin (757), 

 and named by him Paraplasma flavigenum, may be allied to 

 the piroplasms. 



The investigations upon these organisms carried on during the 

 last few years have led to their being divided up into a number of 

 genera based on differences of form and structure. The following 

 enumeration of the genera of " Piroplasmidoe " may serve at the 

 same time to indicate the structural varieties exhibited by these 

 parasites (compare Fraii9a, 736). 



(1) Piroplasma, Patton (Babesia, Starcovici). Pear-shaped forms, 

 dividing by a process of gemmation hence commonly found in 

 pairs in the corpuscle. Species are known from oxen, sheep, horses 

 (P. caballi of " biliary fever "), dogs, monkeys, rats, and various 

 wild animals. 



(2) Theileria, Bettencourt, Fran9a and Borges. Bacilliform or 

 rod-shaped parasites arranged in a characteristic figure of a 



