092 11. M. WOODCOCK. 



is from a redpoll culture of nine days, and figs. 142-144 from 

 one of nineteen days. The body is fusiform to long and 

 slender in shape. The two nuclei are situated distinctly in 

 the flagellar half of the body ; they lie usually fairly close 

 together. The appearance of the flagellar end of the body 

 and its relation to the flagelluni is in general intermediate 

 between that found iti the trypanomonad type and that in a 

 tj^pical herpetomonad form. The flagelhim itself is only 

 connected with the body for a comparatively short distance, 

 and is usually not obviously attached along one side of the 

 body to any extent (figs. 140, 141, 148, and 144) ; hence there 

 are no indications of an undulating membrane. This proximal 

 portion ot" the flagellum is, in the majority of cases, chiefly 

 intra-cytoplasmic, constituting simply a rhizoplast, and corre- 

 sponding to the i-hizoplastic part of the flagellum in the 

 trypanomonad forms (before it passes to the surface to become 

 the border of the membrane). On the other hand, the flagellar 

 end of the body, while sometimes fairly sharp and acute, 

 approximating to the condition in an ordinary herpetomonad 

 (cf. figs. 140, 141, and 147), may taper more or less gradually 

 (figs. 142, 144, and 145) ; hence, in these cases, where it is drawn 

 out a little with the flagellum, the latter may be regarded as 

 "attached" for a short — or very short, distance. For this 

 reason, and because the two nuclei are closer together than is 

 customary in a herpetomonad, this condition is preferably 

 distinguished as pseudo-herpetomonad. The difference will 

 be readily understood when it is remembered that all these 

 individuals are derived from trypanomonad forms by the 

 more or less complete loss of the undulating membrane and 

 its attached flagellar border; hence, of course, parasites 

 showing' all manner of intermediate stages in the process ai*e 

 to be met with. 



In the early formed individuals of this pseudo-herpeto- 

 monad variety there is nothing about them to indicate that 

 they are actuall}' abnormal or unhealthy. As I shall discuss 

 subsequently, however, I think it is very probable that the 

 occurrence itself of this unusual condition is the consequence 



