Sporozoa 309 



parva (21), is not known to occur in Babesia. The supposed absence, in 

 Theileria, of erythrocytic reproduction — a process generally accepted for 

 Babesia — may not be a completely valid distinction. Erythrocytic stages 

 of Theileria parva (21) may undergo a certain amount of growth and 

 possibly reproduction as well (Fig. 6. 23, I-P). Such apparent differences 

 in life-cycles form the basis for the usual recognition of two families, the 

 Babesiidae and Theileriidae, with the general characteristics of their 

 type genera. 



Genera of uncertain status. Two additional genera, Dactylosorna Labbe 

 and Toxoplasma Nicolle and Manceaux, may or may not belong in the 



Fig. 6. 25. A-D. Dactylosoina ranaruin ('Kvuse) Labbe. x2835 (after 

 Mathis and Leger): multinucleate schizont (A), merogony (B), microgame- 

 tocyte (C), niacrogametocyte (D). E-K. Dactylosorna jahni, xl985 (after 

 Nigrelli): parasite entering erythrocyte of a newt (E); stages in reproduction 

 (F-I); microgametocyte (J); niacrogametocyte (K). L-O. Toxoplasma canis, 

 x2875 (after Ray): extraccllidar forms seen in smears from liver and spleen 

 (L, M); binucleate form (X); stage in nuclear division (O). P-U. Toxoplasma, 

 a strain of human origin maintained in mice (after Cross): P. Two parasites 

 in a polymorphonuclear cell, x2500. Q. Group of parasites in a large mono- 

 nuclear leucocyte, x2500. R. Extracellular stage showing nucleus, thick para- 

 style, and cytoplasmic granules. S, T. Nuclear division, Feulgen preparations. 

 U. Binucleate stage with two parastyles; R-U, x4500. 



