21 



Schizogony. (Figs. 1-6). Sporozoite penetrating a red blood 

 corpuscle and developing into a schizont. Nuclear multiplication. 

 Schizogony, producing merozoites. 



Gamete-development. Under certain conditions there appear 

 sexual forms whose further development can take place only in the 

 body of a mosquito. (Figs. 7-11). Macrogamete corresponding to 

 the egg. Maturation. Microgametoblast from which develops the 

 microgametes. Fertilization. Migratory ookinete penetrates the 

 epithelium of the mosquito's stomach, (cf. the encysted oocyst of 

 Coccidium,) . 



Sporogony — Oocyst in submucosa of mosquito intestine. Forma- 

 tion of sporoblasts. Sporozoites. Escape of sporozoites into body 

 cavity and collecting in salivary glands. 



Dissemmination of disease. Solely through mosquitoes of the 

 genus Anopheles. Methods of control considered more fully in 

 discussing mosquitoes. 



Babesia bovis — {Pyrosoma higeminum Smith and Kilborne; 

 Piroplasma higeminum Patton.) The "Texas fever" organism, 

 discovered by Smith and Kilborne, 1893. 



Form and habitat of asexual phase — Lives within the red blood 

 corpuscles and in fresh preparations appear as minute homogeneous 

 pale pear-shaped spots, usually two in a corpuscle. From 2-4/^ in 

 length and 1.5-2/* at widest portion. The common appearance of 

 two associated parasites is due to dividing forms. Live at expense 

 of red corpuscles, as many as 50 per cent of which may be infested. 

 Bloody urine, characteristic of disease, due to breaking down of 

 corpuscles. 



Life cycle — Transferred from animal to animal solely by cattle 

 ticks (Boophilus annulatus) of the second generation. By analogy, 

 a sexual cycle in the tick, but it has not been satisfactorily worked 

 out. Note that we have here a case of true hereditary transmission 

 of a disease, the adult ticks passing it on to the second generation 

 which, in turn, infects cattle. 



Methods of control — Primarily a problem in economic entomology, 

 — the protection of cattle from the tick and the extermination of the 

 tick. 



Related species — Babesia parvum, in African cattle; B. canis, 

 in dogs; B. ovis, in sheep; and various others, causing similar 



