INFECTION 



355 



o.2too.5//in diameter. They are situated within the cor- 

 puscle on its border. As a rule only one is found in a 

 corpuscle. Sometimes a division was evident 

 separating the parasite into two parts. They 

 must be differentiated from somewhat similar 

 looking bright bodies which are seen in the cor- 

 puscles of healthy blood during different seasons 

 of the year. 



Concerning the life history of this parasite, 

 Smith considered the intraglobular stage hypo- 

 thetically the swarming stage, which precedes F1G.93. Blood 

 the peripheral coccus-like bodies and the pyri- in capillary of 

 form and spindle shaped bodies which develop heart show- 



from the divided coccus-like peripheral forms. ^^ , ,V''t,"f' 



"^ -^ ma {Sntzth). 



The free bodies are the parasites set free after 



they have reached the preceding stage by disintegration of 

 the infected corpuscles. They are most commonly found in 

 the kidney. The reproduc- 

 tive stage has not been recog- 

 nized. 



§ 268. Infection. Al- 

 though practical stockmen 

 had long looked upon the 

 tick as a source of infection, 

 it remained for Smith and 

 Kilborne to experimentally 

 demonstrate that so far as 

 known the cattle tick {Bobphi- 

 lus annulatus)* is the sole carrier of the parasite. It was 

 pointed out by them that when southern cattle were freed 



Fig. 94. Sexually mature male 

 tick after the last >noult, dorsal 

 view {Smith). 



*This tick was first described by C. V. Riley in 1868 as Ixodes bovis. 

 Later, Cooper Curtice investigated this parasite (Biology of tlie Cattle 

 Tick, Journ. Comp. Med. and Veterinary Archives, July, i89i,Jan., 

 1892) and gave it the generic name of Boophilus {os. loving). This 

 seems to be the only genus of cattle ticks which transmits the parasite 

 of Texas fever. Recently Karsch's genus Margaropus has been pro- 

 posed as the correct name instead of Boophilus. 



Digitized by Microsoft® 



