240 



TEXAS FEVER 



Fig. 57. Cover-glass pre 

 paration from kidney. Cor 



blood corpuscles in the capillaries were 

 more and in still others less exten- 

 sively infected. In the living blood 

 the parasites were p^-riforni, but in 

 the post mortem specimens, they were 

 more nearly round. In the mild type 

 of the disease from 5 to 50 per cent of 

 the red corpuscles in the circulation 

 are infected for a period of from one 

 to five weeks. The parasite is round 

 (coccus form). In the fresh prepa- 

 rations it is seldom seen ; rarely it can 

 be detected as a pale spot about 0.5// 

 in diameter at the periphery of the 

 piiscles sho-ccntig piropleis- corpuscle. In stained (alkaline me- 

 ma, coccus form. (5'«"'''0 ■ ti,yiene blue) preparations, the para- 

 sites appear as round coccus-like bodies from 0.2 to 0.5/' in 

 diameter. They are situated within the corpuscle on its 

 border. As a rule only one is found in a corpuscle. Some- 

 times a division was evident separating the para- 

 site into two parts. They must be differentiated 

 from somewhat similarly looking bright bodies 

 which are seen in the corpuscles of healthy 

 blood during different seasons of the year. 



Concerning the life history of this parasite, 

 Smith considered the iutraglobular stage 

 hypotheticallj' the swarming stage, which pre- 

 cedes the peripheral coccus-like bodies and the 

 pyriform and spindle shaped bodies which de- 

 velop from the divided coccus-like peripheral 

 forms. The free bodies are the parasites set 

 free after they have reached the preceding 

 stage b}' disintegration of the infected corpus- 

 cles. They are most commonly found in the kidney 

 reproductive stage has not been recognized. 



§182. Infection. Although practical stockmen had long 

 looked upon the tick as the source of infection it remained for 

 Smith and Kilborne to experimentally demonstrate that so far 



Fig. 58. 

 Blood in cap- 

 illaryof heart 

 showing Pi- 

 rop la s m a. 

 (Smith). 



The 



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