ATKLCAN TICK FEVER 501 



practically identical, although Koch thought that the organisms 

 in tick fever tended on the whole to be slightly longer; the 

 average length may )>e said to be 15 to 35 JJL. Button and Todd 

 showed that it was possible to transmit the disease to certain 

 monkeys (cercopitheci) by means of ticks which had been allowed 

 to bite patients suffering from the disease, the symptoms in 

 these animals appearing about five days after inoculation. The 

 disease thus produced is characterised by several relapses, and 



o - - 



FK.. 151. Spirillum of human tick fever (Spirillum Duttoni) in 

 blood of infected mouse, x 1000. 



often leads to a fatal result. In one case they produced the 

 disease by means of young ticks hatched from the eggs of ticks 

 which had been allowed to suck the blood of fever patients, and 

 they came to the conclusion that the spirochaetes were not simply 

 carried mechanically by the ticks, but probably underwent some 

 cycle of development in the tissues of the latter. The species of 

 tick concerned is the onutkodonu moubata. These results were 

 confirmed and extended by Koch. He found that after the ticks 

 had been allowed to suck the blood containing the organisms, 

 could be found for a da or two \n the stomachs of ^he 



