SPOTTED FEVER. 721 



connected by a fine filament. They occur both in 

 the red corpuscles and in the plasma. As they 

 grow larger, two to three by three to five microns, 

 only one parasite usually is found within an ery- 

 throcyte, and in this stage they show active ame- 

 boid movement with the formation of pseudopodia. 

 Eventually they assume a spherical form in fresh 

 preparations. They were able to transfer the in- 

 fection to rabbits by the inoculation of infected 

 blood. 



After identifying the organism as a piroplasma 

 and having in mind the part that ticks play in the 

 transmission of Texas fever, and perhaps piroplas- 

 mosis in other animals (horse, sheep, dog), Wilson 

 and Chowning directed their attention to the ques- 

 tion of tick bites in those who become infected. 

 It developed that of the twenty-three cases exam- 

 ined in 1903 all had been bitten by ticks, and 

 fourteen had been bitten in from two to eight 

 days before the onset of the disease. They con- 

 cluded that the disease is transmitted in this 

 manner. 



They also searched for some other host than 

 man, in which the parasites might flourish contin- 

 uously and constitute a source of infection for the 

 ticks. This they believe was found in a certain 

 gopher (Spermopliilus columbianus) . On the west 

 side of the river that side in which the disease 

 attacks man they found the erythrocytes of about 

 20 per cent, of the gophers infected with a parasite 

 similar to that found in man. On the other hand, 

 the blood of sixty-two gophers from the uninfected 

 side of the river showed no parasites. "Early in 

 the spring the spermophile is said to harbor great 



