TRYPANOSOMES IN TSETSE-FLIES AND OTHER DIPTERA. 201 
but among the many thousands of trypanosomes that have 
passed under my vision I have found none that could be 
interpreted with certainty as conjugating forms, and very 
few which could. be suspected of this. Since conjugating 
forms might conceivably be confused with dividing forms, I 
studied in detail, and have described above, the process of 
division and its variations, which are chiefly variations in the 
rapidity, relative to one another, with which the flagellum 
and the two nuclei (x and N) divide. I have found a few 
specimens which might perhaps be conjugating forms, and have 
figured three of them. In one (fig. 214) it is seen that the 
two flagella are widely separate, that there are two large 
kinetonuclei in close contact, and that there is a single com- 
pact nucleus, very dense in texture. If this be a variation of 
division, it is a remarkable one, not only in the very pre- 
cocious division of the flagellum, and in the fact that the body 
has begun to divide before the nucleus has divided, but, above 
all, in the very large size of the two kinetonuclei; I have 
never seen any division-stage in which the daughter-kineto- 
nuclei were of such large size. On the other hand, this 
specimen would very well bear interpretation as a fusion, 
which had commenced from the hinder end of two individuals, 
in which the bodies are nearly fused, the nuclei completely so, 
the kinetonuclei are beginning to unite, and the flagella are 
still quite separate. If this interpretation be the right one, 
fig. 216 might possibly represent a further stage of the same 
process. Another possible instance of conjugation is seen in 
fig. 143, in which the kinetonuclei are united, while the nuclei 
are distinct. If these three figures really represent instances 
of conjugation,! they do not throw much light on the 
characters of the males and females, except to show that one 
1 The forms figured by Stuhlmann (41) and interpreted by him as conjugation- 
stages are very different in appearance, especially in having the two flagella on 
the outer sides, furthest from each other, instead of close together. Stuhlmann 
considers the position of the flagella diagnostic of conjugation as compared 
with division; this makes it still more doubtful if the forms figured by me are 
really conjugation-stages. 
