BABESIA, 303 



species, Piroplasma tropicus, instead of to several previously 

 described species, such as P. bigeminum, P. canis, P. bovis, 

 P. ovis, etc. Yakimoff (1931), after reviewing the previous 

 classifications of Piroplasma, divides the genus into two 

 subgenera, as follows ; — 



(1) Of typical pyriform shape, often in pairs. Length 

 of pyriform organisms greater than the radius of the erythro- 

 cyte. Situation in the corpuscle central. Pyriform indi- 

 viduals of a pair form an acute angle. Number of chromatin 

 masses in budding pear-shaped forms not less than two. 

 Pear-shaped forms more numerous than the round forms. 

 Trypan blue effective. Species included are P. bigeminum, 

 P. caballi, P. canis, P. motasi \_=^P. avis']. Subgenus Piro- 

 plasma s. str. 



(2) Form pear-shaped (lancet-shaped), annular or elhptical. 

 Length of the pear-shaped forms smaller than or equal to the 

 radius of the erythrocyte. Situation in corpuscle peripheral 

 or central. Pyriform individuals of a pair form an obtuse 

 angle. In the pear-shaped forms there is a single chromatin 

 mass. Round forms predominate over the pear-shaped ones. 

 Trypan blue may or may not be effective. Subgenus 

 Babesiella Mesnil, 1919. 



The subgenus Babesiella is further subdivided into species 

 groups as follows : — 



Group 1. Babesiella s. str. Form smaller than the radius 

 of the erythrocjrte ; situation peripheral ; trypan blue 

 effective B. bovis. 



Group 2. Frangaiella. Form smaller than or equal to 

 the radius ; situation central ; trjrpan blue not effective. 



(a) Form equal to radius . . F. colchica, F. major. 

 (6) Form less than the radius. F. argentina, F. berbera, 

 F. caucasica, F. occidentalis. 



This scheme is convenient for diagnostic purposes, but 

 obviously the names Babesiella and Frangaiella cannot be used 

 in a generic sense. 



253. Babesia bigemina (Smith & Kilborne). (Fig. 147.) 



Pyrosoma bigeminum. Smith & Kilborne, 1893 a, p. 67 ; 1893 b, 



p. 511, fig. 1 ; Starcovici, 1893, pp. 1-8. 

 Piroplasma bigeminum, Labbe, 1899, p. 194, fig. 195 ; Minchin, 



1903, pp. 242, 262, 269, 338, 350. 

 ■^Piroplasma bigeminum, Lingard, 1903. 



"^Piroplasma sp. (probably bigeminum), Donovan, 1903, p. 1401. 

 ■\Piroplasma bovis, Stephens & Christophers, 1904, pp. 333-4, 



pi. iii. 

 ■\Piroplasma bigeminum, Hohnes, 1904, pp. 317-26, 1 pi. ; Lingard 

 & Jennings, 1904, pp. 161-5, pi. i, figs. 4, 5 ; 1907, pi. vii, fig. G, 9. 

 Piroplasma bovis, Nuttall & Graham-Smith, 1908, pp. 138-9, 

 diagrana ii. 



