STUDIES ON AVIAN H.EMOPBOTOZOA. 693 



merely of the unusual euviroumeut ; I am very doubtful 

 whether it can be regarded as representing a normal phase 

 of the life-cycle. In any case^ however, as the age of a 

 culture increases, and these fonny multiply and predominate 

 — the trypanomonad phase as quickly declining — numerous 

 irregular forms of the parasites are met with, which are 

 manifestly unhealthy. As might be expected, the form and 

 size of these individuals varies considerably (cf. figs. 145— 

 154, taken either from a twelve-day chaffinch culture or from 

 a nineteen-day one from a redpoll). Some of them are long 

 and narrow, others pear-shaped, while others are large and 

 massive, ovoid, or of ill-defined shape. 



The abnormal condition of these forms is particularly 

 indicated by certain cytological characters, which I have 

 never observed in normal individuals. A common feature is 

 the occurrence of a peculiar altered appearance in the neigh- 

 bourhood of the rhizoplastic part of the fiagellum. Some- 

 times there is a cluster of red-staining granules in this region 

 of the cytoplasm (figs. 145, 146). In the more massive 

 forms there is usually a greater or less amount of a diffuse, 

 indefinite substance, which also stains red. This substance 

 is often more or less streaky in form, one or more streaks 

 commencing in the neighbourhood of the rhizoplast and 

 running" backwards in the cytoplasm for a short distance 

 (figs. 150, 151, and 153). In a few individuals the streaky con- 

 dition is combined with the occurrence of the granules (fig. 152). 

 I am unable, unfortunately, to offer any certain explanation 

 of this interesting character, owing to the fact that I have 

 only had material stained with Giemsa in which to observe 

 it ; very likely the appearance is different after other methods 

 of staining. So far as the granules are concerned, they do 

 not differ in their staining reactions from the ordinary 

 chromatoid granules which are often found in normal 

 trypanomonad types ; the latter, however, are scattered more 

 or less generally throughout the body, whereas the particular 

 granules under consideration are always concentrated near 

 the rhizoplast. Hence, it is not certain that the granules 



