670 MURIEL ROBERTSON. 
twice or thrice the*léength of the Trypanosome. ‘This last 
movement is familiar to observers who have worked with 
Spirocheetes, only in these it is intensely rapid, while in the 
case of the Trypanosomes it is quite a slow movement. 
In most infections small Trypanosomes (Pl. 16, figs. 5—7) 
are to be seen, less than half the size of the average speci- 
mens. In these the membrane is generally a little wider 
relatively than in the case of the larger forms, and the part 
of the body posterior to the kinetonucleus is much shorter 
and generally more pointed. The protoplasm is usually 
rather hyaline. I do not think that these small specimens 
belong to a separate species, as forms intermediate in size are 
also to be seen. Further, these small creatures take part 
equally in the developmental process to be described pre- 
sently. Iam, however, ignorant of their origin. 
Another variation, only rarely met with, is that some 
specimens have the trophonucleus very much further for- 
ward than is usual. These creatures were present in small 
numbers only in one infection. ‘The ordinary forms were 
also present. I cannot be certain as to whether they belong 
to the same species or not, but am personally inclined to 
think that they do. 
There is always a considerable variation in the size and 
thickness of the Trypanosomes, and also, to a certain extent, 
in their staining reactions; but it is not marked enough for 
there to be any reason, in my opinion, for dividing them 
into male, female, and indifferent upon their morphological 
characters. This type of difference between the forms is 
much less evident than, for instance, in such a 'T'rypanosome 
as T. brucei. 
Longitudinal division does occur, but it is only very rarely 
to be seen, even in good infections. Specimens with two 
trophonuclei are very occasionally to be seen; it so happens 
that I have seen these chiefly among the intermediate sized 
forms. 
If blood infected with Trypanosoma vittatz is placed 
upon a slide, covered with a coverslip and sealed with vase- 
