STUDIES UN AVIAN H^JIOPROTOZOA. 679 



of the infection in this later case B, the chaffinch in which 

 there was also an abundant halteridial infection. As I have 

 stated in my note (38) on this interesting Halteridium, I 

 was at the time inclined to think that the very small trypano- 

 somes might have been developed directly from the 

 Halteridia. Paying attention, for the moment, only to the 

 trypanosome side of the question, in addition to the faet that 

 in this case we have certainly to do, not with division, but 

 with growth and increase in size from the minute forms up to 

 comparatively large ones, there were other reasons which led 

 me to take this view. This chaffinch, originally free from 

 trypanosomes, was inoculated with cultural forms, but the 

 subsequent course of events was very different from that in 

 the case of the other successful inoculation described. In the 

 latter case the parasites soon became comparatively numerous 

 in the blood, whereas in the former they were not found at 

 all at first, and only after some weeks were they shown to 

 be actually present, by tubing (for further details, cf .p. 660). 

 When at length they did become sufficiently numerous to 

 be found without difficulty in stained preparations, they 

 proved to be, as Ave have seen, quite different in form from 

 the ordinary individuals developed in the other case. Hence, 

 takino- all thingrs into consideration, I considered that the 

 trypanosome infection was probably not due to the inocula- 

 tion (which, in several cases, it must be remembered, did fail), 

 but to the presence of Halteridiura. 



I admit now that I have changed my opinion about this 

 case since writing my former note. In spite of the many 

 features which seemed either to point strongly to this view, 

 or at least to favour it, I think after all the trypanosome 

 infection was not really connected with the Halteridial one, but 

 was due to the inoculation (for further discussion of this subject, 

 see under Halteridium). There remains the question. Why 

 was the course of the infection so different in the two cases ? 

 Of course, in the one case where the parasites developed 

 quickly, the inoculation was made with cultural forms which 

 had come from a redpoll, while in the other they came from a 



