624 



PROTOZOOLOGY 



embryonic tissue cells of tick, many of which cells develop into 

 salivary gland cells; sporokinetes develop into sporozoites before or 

 after hatching of host tick; sporozoites bring about an infection to 

 cattle when they are inoculated by tick at the time of feeding. Texas 

 fever once caused a considerable amount of damage to the cattle 

 industry in the southern United States to which region the distribu- 

 tion of the tick is limited. Rees (1934) maintains that there is in 

 addition a somewhat smaller species, B. argentina Lignieres. 



Fig. 269. a-d, Babesia bigemina, X3Q00 (Nuttall); e-h, B. bovis, 

 X3000 (Nuttall); i-1, Theileria parva, X3000 (Nuttall); m-s, Dactylo- 

 soma ranarum (m-q, schizogony; r, s, gametocytes), X2700 (Noller). 



B. bovis Starcovici (Fig. 269, e-h). In European cattle; amoeboid 

 form usually rounded, though sometimes stretched; 1-1. 5m in dia- 

 meter; paired pyriform bodies make a larger angle, 1.5-2/* long; 

 transmitted by Ixodes ricinus. 



B. canis (Piana and Galli-Valerio). Pyriform bodies 4.5-5/x long; 

 the organism causes malignant jaundice in dogs; widely distributed; 

 transmitted by the ticks: Haemaphysalis leachi, Rhipicephalus san- 

 guineus, and Dermacentor reticulatus (Regendanz and Reichenow, 

 1933). 



