STUDIES ON AVIAN H^MOPKOTOZOA. 689 



were very active, travelliug- much more rapidly than was 

 customary in the case of these cultural forms. In the coui-se 

 of looking for halteridia on a permanent smear (made at the 

 same time), I happened very fortunately to come across a 

 trypanosome, and this was so different from the usual trypa- 

 nomonad type that I subsequently examined my preparations 

 of this series thoroug-hly to ascertain whether this was the 

 prevailing type. Unfortunately the trypan osomes are very 

 scarce, only three or four on a large film. It is noteworthy, 

 however, that all the parasites seen as a result of systematic 

 searching are in the same trypaniform phase, and show only 

 slight individual variations. 



The type is extremely thin and slender, the parasite having 

 a distinctly vermiform appearance (figs. 10, 126, and 127). The 

 body is from 21 to 25/iin length, excluding the flagellum, 

 and its greatest breadth only from Ij to 1^^. The aflagellar 

 region is very long and finely tapering. The kinetonucleus 

 is far removed from the trophonucleus, and generally lies 

 about midway between the latter and the aflagellar extremity. 

 Its actual distance from this end varies from 6 to 9^, depend- 

 ing upon the degree of attenuation. The undulating mem- 

 brane is in most cases very narrow, and practically distin- 

 guishable only by its flagellar border. In some individuals 

 the flagellar border originates, not in close proximity to the 

 kinetonucleus, as is usually the case, but from a point some 

 little distance beyond, i.e. on the aflagellar side of the 

 kinetonucleus (figs. 10, 127). A distinct granule (blepharo- 

 plast or basal granule) can often be made out at its com- 

 mencement. The length of the free flagellum is from 8 to 

 11/t. The trophonucleus, instead of being the usual shape, 

 namely, oval or rounded, is considerably elongated in the 

 long axis of the body, this being in relation, in all probability, 

 with the narrow form. 



The other instance of the occurrence of parasites of a 

 trypaniform type in my cultures was in a series from a six-day 

 (original) culture of the chaffinch-form, taken when the 

 trypanosomes, of the ordinary, definitive type, were very 



