STUDIES ON AVIAN H^EMOPROTOZOA. 665 



extreme types noticed and serve to connect them. Lastly, 

 it may be added that the various cultural forms to which the 

 parasite from the chaffinch gives rise are quite similar to, 

 and cannot be distinguished from, those developed from the 

 trypanosome of the redpoll. 



The ordinary or definitive type of T. f r in gill in arum is 

 elongated and slender in appearance (figs. 1-4, 27, and 28) 

 The aflagellar end is long and finely tapering, at times being, 

 indeed, extremely attenuated (fig. 27).^ The free flagellum 

 is usually comparatively short. The trypanosome possesses 

 a well-developed undulating membrane, which has three or 

 four folds or pleats, broad and deep. The average dimeii- 

 sions of a full-sized " adult " individual are as follows : 



Total length, including flagellum . 



Greatest width, including undulating 

 membrane ..... 



Greatest width of undulating mem- 

 brane ...... 



Length of tapering aflagellar poi'tion of 

 body, i. e. the distance from kine- 

 tonucleus to extremity 



Length of free flagellum 

 The trophonucleus (nucleus) is situated near the middle of 

 the body, often slightly in the aflagellar half. It lies gene- 

 rally somewhat nearer to the undulating membrane than to 

 the opposite side. The nucleus is more frequently ovoid in 

 shape, but it may be approximately round (figs. 1 and 29) ; 

 in the former case it may measure as much as 3 ^ by 2 //, 

 and in the latter case it may have a diameter of 2^/n; but 

 these dimensions are not always attained. 



The kinetonucleus appears as a relatively lai*ge body, 



1 This aflagellar prolongation is very delicate and liable to be broken 

 off and lost in the preparation of the specimen ; hence, now and again a 

 parasite is seen wliicli appears to have no " snout " at all, and where the 

 body appears to be terminated by the kineto-nuclens ; this is certainly 

 an artificial condition, for it is characteristic of the fully grown ordinary 

 individuals to have this long attenuated process at the aflagellar end. 



