« GRANULE-CLUMPS » AND SPIROCHAETES 55 



was motionless and corresponcled in every particular to the 

 isolated granule clumps to which I hâve so trequently alluded. 

 Still later, as one continues to follow the course of events in 

 the batch of ticks, there occurs a period of a few days during 

 wliich either no spirochaetes at ail can be detected or only 

 verv rare ones wliicli are seldom motile. Next, and most 

 prominently in Ihe case of ticks which hâve been kept at com- 



FlGURE I. 



N»' 1-6. — « Granule-clumps » from Ihe lissues of Ornithodorus moubata. 



N"^ 7-10. — Early stage in the extrusion of Spirochaetes from granule- 

 clumps. 



Nos 11-21. — More advanced stages of extrusion of Spirochaetes from 

 granule-clumps. 



paratively high températures' (I hâve experimented with 

 batches kept at 22°, 24% 27«, 30°, 32% 34% and 37'' C.) there 

 appears a sudden re-invasion of the tissues with numerous and 

 vigorously motile spirochaetes. In some instances I hâve been 

 able to observe that a large proportion of the spirochaetes 

 which re-appear in this sudden and wholesale fashion arc very 

 différent in size and gênerai appearance from those which were 

 originally ingested by the tick and which retained their mor- 



