192 



Diseases of Poultry 



destruction of the parasites by the large leucocytes of the 

 spleen and liver. The organisms are carried from one fowl 

 to another by the tick Argas (see p. 228). According to 

 von Prowazek ^ the tick is a true intermediary host, the 

 organisms appearing in the salivary glands about 14 days 



X"^ 



Fig. 35. — Fowl spirochaetosis. (From KoUe and Ketch, after Burri.) 



after infection. The organisms may live in the body of 

 the tick for seven or eight months. That the tick is not a 

 necessary host is shown by the fact that injection of the 



1 Von Prowazek, S., Mem. Inst. Oswaldo Cruz. T. I, pp. 79- 

 80, 1911. 



