STUDIES ON AVIAN HiEMOPEOTOZOA. 721 



namel}', in the length of the free flagellum, which is much 

 sliorter, and in the appearance of the aflagellar end, which is 

 more elongated and attenuated. In addition, the hosts are, 

 of course, quite different in the two cases. 



Novy and McNeal have included in the species T. avium 

 a number of pai-asites they have found in various North 

 American birds. They distinguish two chief forms, viz. large 

 and small parasites, each of which shows considerable varia- 

 tions in size. How Novy and McNeal have been able to 

 ascertain any details with regard to form and size, if they 

 had not better preparations to study than those from which 

 their excellent photos have been taken, it is impossible to say. 

 From their photos of the parasites in the birds, it is obvious 

 that the trypanosomes were wretchedly fixed and stained; in 

 scarcely any can the length of the flagellum or the true 

 nature of the aflagellar end be made out. Hence, any real 

 morphological comparison is out of the question. In any 

 case, on the grounds of occurrence and distribution, it is very 

 improbable that any of the parasites represented the true T. 

 avium. This has been recognised by Liihe (9), who has 

 placed all these forms identified by the Americans as T. avium 

 in a new species, T. confusum — a very apt name. I do not 

 for a moment suppose, however, that all the forms described 

 belong to one species. Novy and McNeal rely partly on the 

 cultural characteristics shown, which they say were similar in 

 all these cases. All their photos of cultural forms of this 

 group of trypanosomes are taken from preparations of a single 

 culture, fi-om one bird only. I should prefer to see figures of 

 cultural forms from the other birds first of all. 



The trypanosome which Novy and McNeal distinguish as 

 T. laverani, from an American goldfinch, Astragalinus 

 tristis, is most probably closely related to T. fringilli- 

 narum, although I am hardly inclined to think the two forms 

 are identical. The authors only figure a solitary example 

 from the blood, which, from the size given, and from what can 

 be made out from the photo, agrees very Avell with the small, 

 fusiform individual of T. f ringillinarum. There is a 



