CHAPTEK XLI. 



PIROPLASMA BIGEMINUM THE MICROSPORIDIA BALANTIDIUM 



COLL 



Genus Piroplasma Smith and Kilborne (1893). 



IT was riot until 1888 that there was a hint as to the real nature of the 

 actual cause of "Texas fever" and allied diseases which attack field 

 cattle in many parts of the world. Then Babes described inclusions in 

 red blood cells in Roumanian cattle sick with the disease, though he 

 did not decide upon the nature of the organism. No new studies were 

 reported until 1893, when Theobald Smith and Kilborne gave such a 

 complete description of this disease and its cause as occurring in Texas 

 cattle that little that is new has since been discovered. 



These authors describe as the cause of Texas fever pigment-free, 

 amoeboid parasites appearing in various forms within the red blood 



cells of infected animals. The organ- 

 isms may be irregularly round and lie 

 singly or they may be in pear-shaped 

 twos, united by a fine line of protoplasm. 

 Because of these double pear-shaped 



Piroplasma bigeminum showing pear- forms g mith Rnd Kilborne named the 

 shaped forms in curved and straight . , 



axes. (After Kossei and weber.) organism pyrosoma bigemmum 1 and 



placed it among the haemosporidia. 



These authors also showed that the contagion was carried by a tick 

 (Boophilus bovis). Their work has been corroborated by many investi- 

 gators in different parts of the world. 



Morphology of the Parasite. In the examination of fresh blood of 

 sick cattle under 1000 diameters, according to Smith and Kilborne, 

 are seen, in the red blood cells, double pear-shaped forms and single 

 rounded or more or less irregular forms. The size varies, though gen- 

 erally it is the same among the bodies in the same red blood cell. The 

 average size is 2/J. to 4/* long and 1^/e to 2/* wide. The pointed ends of 

 the double form are in apposition and generally touch, though in 

 unstained specimens a connection between them cannot be seen. The 

 axis forms either a straight line or an angle. The protoplasm has a 

 pale, non-granular appearance, and is sharply separated from the proto- 

 plasm of the including red blood cell. The small forms are generally 

 fully homogeneous, whereas the larger ones often contain in the rounded 

 ends a large rounded body, O.I// to 0.2// in size, which is very glistening 



1 The generic name Pyrosoma, already in use for a well-known Ascidian genus, was altered to 

 Piroplasma by Patton in 1895. 



