STUDIES ON AVIAN H^EMOPROTOZOA. 681 



that it is of very great service in ascertaining whether a 

 bird is infected with trypanosomes or not. I think now 

 that I must have been unusually fortunate in my first 

 experiences of the culture method.^ T had no difficulty in 

 getting the parasites to develop in my cultures, and, more- 

 over, in a perfectly healthy manner. I soon had no trouble 

 in distinguishing between what could be regarded as normal 

 types, of regular occurrence, and what were abnormal, irre- 

 gular forms. Hence, I admit that I modified my former 

 attitude towards this method, and came to the conclusion 

 that the cultural forms were probably, for themselves, well 

 worth studying. I claim some excuse for my earlier opinion, 

 since at that time this method had only begun to be adopted 

 for trypanosomes, and in the eai'ly descriptions of cultural 

 forms most of the figures depict what can only be described 

 as altered appearances, which certainly belong to the cate- 

 gory of abnormal phases. As a result of my own work, the 

 view I now hold, and which I have expressed in my article 

 in Lankester's 'Protozoa' (39), is that the cultural forms of 

 trypanosomes may afford indications of value as to the 

 developmental phases of the parasites occurring in the 

 invertebrate host. 



As I have already indicated, the chief cultural forms 

 developed from the trypanosomes in the redpoll are quite 

 similar to, and practically indistinguishable from, those to 

 which the parasite from the chaffinch gives rise. I have 

 had, however, a much greater number of successful cul- 

 tures from the latter bird tlian from the former; hence I 

 have found a greater variety of intermediate phases in my 

 cultures from the chaffinch, and have had the good fortune, 

 moreover, to observe one or two particular phases which I 

 have not seen in cultures from the redpoll. This is doubt- 

 less due, however, mei'ely to lack of sufficient material in the 



1 I may mention incidentally that I have since had a full measure of 

 the trials and troiibles which may attend the cultural method, for at 

 Rovigno, in connection with the trypanosomes of the little owl, I had no 

 success at all with it. 



