330 TEXAS FEVER 
the living blood the parasites were pyriform, 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 preparations it is seldom seen; 
rarely it can be detected as a pale spot about 0.5¥. in diameter at the 
periphery of the corpuscle. In stained (alkaline methylene blue) 
preparations, the parasites appear as round coccus-like bodies from 
0.2 to 0.54% in diameter. They are situated within the corpuscle on 
its border. As arule only one is found in a corpuscle. Sometimes a 
division is evident separating the parasite into two parts. They 
must be differentiated from somewhat similar looking bright bodies 
Fig. 78. BLOOD 
IN CAPILLARY 
OF HEART Fic. 79. SEXUALLY MATURE 
S HOWING MALE TICK AFTER THE LAST 
PTR O PLASMA MOULT, DORSAL VIEW 
(Smith). (Smith). 
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 
intraglobular stage hypothetically the swarming stage, which precedes 
the peripheral coccus-like bodies and the pyriform and spindle shaped 
bodies which develop from the divided coccus-like peripheral forms. 
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 reproductive stage has 
not been recognized. 
Infection. Although practical stockmen had long looked upon the 
tick as a source of infection, it remained for Smith and Kilborne to 
