54 ANNAI.ES DE L'I.NSTITUT PASTEUU 



of service in the présent investigation and it oiight also to bc 

 useful in otlier directions. 



In gênerai, Ihis latcr séries of experiments has been confir- 

 matory of my earlicr ones but, in several instances, I hâve 

 fonnd il necessary to revise my former conclusions in the light 

 of further expérience. It would not, however, be possible, 

 within the necessary limits of this communication, to deal 

 satisfactorilv wilh the whole of the work; so I shall confine 

 myself to a few points, reserving the fuller account for another 

 occasion. 



I fmd that the spirochaetes, after ingestion by the tick, retain 

 their motility for several days, the period depending chiefly on 

 the température at which the ticks hâve been kept. Subse- 

 quently, they lose their motility and tend to agglomerate into 

 great tangles or masses which, when stained, are seen to 

 consist of spirochaetes whose chromatin is fragmented into 

 deeply staining segments or granules. Such spirochœtes 

 I believe to be dead and I think it probable that the segmented 

 chromatin may persist in the form of rods or grains and may 

 reach the Malpighian tubules and other tissues of the tick, 

 accounting in this way for some, perhaps for the majority of 

 the chromatin granules found in such tissues. 



Other spirochaetes, however, appear to behave in a diffé- 

 rent manner and show the curions appearance of a latéral or, 

 more rarely, a terminal protrusion or "bud". This latéral bud 

 was described by me in my earlier papers and has also been 

 observed by many others, both in connection with Spirochaeta 

 duttoni and other spirochaetes. I am now inclined to attribute 

 to it an important rôle in the life of the organism, as I believe 

 it to be the origin of the granule clump which may subse- 

 quently develope into another spirochaete. I bave, for 

 instance, observed a spirochaete which had one of thèse 

 large latéral bud s attached to it, in active rotatory mo ve- 

 ulent for a period of half an hour; the bud contained 3 or 

 4 highly refractile granules and there could be no possible 

 doubt that the structure was attached to and part of the living 

 organism. At the end of the half hour séparation occurred 

 between the bud and the spirochaete, the latter continuing to 

 rotate and bend for another ten minutes, but the separated bud 



