﻿96 Proceedings of the Royal Physical Society. 



at times of both Hsemogregarines and Spirochsetes, there is 

 also, as the above series of stages show, a very strong 

 Herpetomonad affinity. I also wish to point out that the 

 position in the body of the protoplasmic inclusion upon 

 which Dr Woodcock is inclined to lay so much stress, can 

 hardly be held, in the light of these observations, to be of 

 serious morphological importance. 



Trypanosome Stages. 



Amongst the " typical " trypanosomes, that is, those indi- 

 viduals which have their kinetouuclei at or towards the 

 posterior end of the body, and which possess the usual 

 locomotor apparatus, two main types may be distinguished. 

 The most striking of these is a long, slender trypanosome 

 (Fig. 25), with a large kinetonucleus lying occasionally 

 parallel to the longitudinal axis of the body, instead of at 

 right angles to it, as in the Herpetomonas forms from which 

 it develops (Figs. 39-42 h). At the edge of the usually very 

 narrow membrane, there runs the flagellum, which projects 

 to a varying distance beyond the protoplasmic body, but the 

 free part is, as a rule, not very long. 



The nucleus has become modified; the chromatin is no 

 longer disposed in the familiar circle enclosing the central 

 karyosome, but forms a number of transverse rods : the 

 karyosome is often no longer to be distinguished. The 

 different stages by which this form is developed can, upon 

 favourable material, be traced with the utmost clearness. 

 The process is illustrated in Figs. 38-42 h. The difference 

 in the appearance of the trophonucleus is brought about 

 by the narrowing and lengthening out of the structure, the 

 chromosomes from the opposite sides being thus brought 

 into contact with each other across the middle line. This 

 point is shown in Figs. 22, 23, 24, 55, 59, etc. 



In the live state, this slender trypanosome moves very 

 rapidly through space, the motion being executed much 

 more by the whole body and less by the undulating 

 membrane than, for instance, in the case of the ordinary 

 mammalian trypanosomes. The body also gives the impres- 



