50 ANNAI.es de L'INSTITUT PASTEUH 



The ivsiills of soine oi' lliis work were publishcd in 1909 and 

 1910 [1^. 



The piirpose of llic présent note is to record sonie furiher 

 observations vvhich appcar to throw fresh liuht upon the nalure 

 of Ihe granule-clumps, described in the above mentioned 

 paper?, which, I suggested, were probably derived from spiro- 

 chaetes and were capable, under certain conditions, of once 

 again (lev(doping' into spirochaete form. To recall a few of 

 thèse earlier observations; it was noted that thèse granules 

 were almost constantly found in varions tissues oî Ornithodorus 

 and that the inoculation of tissues containing such granules, 

 but, as far as could be delermined, no spirochaetes, frequently 

 resulted in the production of spirocha^tosis in mice. The 

 occnrence of similar granules in the eggs of the fecundated 

 female tick and my almost invariable failure to find spirochaetes 

 in such eggs, even when the mother tick had been heavily 

 infected shortly before, further suggested to me that it might 

 be in this form that the virus passed to the next génération of 

 ticks. 



Some of my experiments hâve since been repeated by other 

 workers, either with Spiroc/iaeta duttoni and Ornithodorus 

 moubata or with Spirochaeta gallinanim and Argas persicus, 

 wilh somewhat contradictory results. Thus, Hindle [2] and 

 Fantham [3] confirmed many of my observations and agreed 

 with mo>t of my conclusions, while strong confirmatory évi- 

 dence was also obtained from Balfour's work on the Spirochae- 

 tosis of Sudanese fovvls [4]. On the other hand, the more 

 récent work of Marchoux et Couvy [5], of Kleine et Eckard [6], 

 of Wittrock [7] and of Todd [8] has led thèse investigators to 

 conclusions differing from mine. They hâve not been able to 

 find any évidence of a connection between the granule-clumps 

 and the spirochaetes and they are satisfied that the facts of 

 transmission, whether direct or hereditary, are to be accounted 

 for more simply by the persistence of the spirochaetes, as such, 

 in the ticks and by their transmission in this form Ihrougli 

 the egg to the young tick. 



I hope before long to hâve an opportunity of putting on 

 record fuller détails of my récent work than are possible in this 

 note and of discussing some of the apparent discrepancies 



