688 MURIEL ROBERTSON. 
the lve observations. As soon as the ‘'rypanosome has 
rolled itself up and cast off its flagellum, the division of the 
nuclear elements begin, and it is at this stage that they are 
to be found in material from the crop. This early part of 
the work has mostly been made out from material from the 
Limnatis (figs. 8—12). 
The two first divisions both of the trophonucleus and 
kinetonucleus follow quickly upon each other, the details of 
division being not so clear as in ‘I’. raiz. Probably this is 
due to the slowness of the process in this last-mentioned 
T'rypanosome, which in conjunction with the rich infections 
found in the intermediate host make the obtaining of a com- 
plete series a comparatively simple matter. 
In the division of the trophonucleus of 'l’. vittatz there 
is a marked resemblance to what occurs in 'l’. raiz ; in fact, 
the two processes are quite parallel. We have here also a 
nuclear division where no equatorial plate is formed, and 
where (figs. 9 and 10) no differentiation of the chromatin 
into chromosomes occurs. In both cases there is a well- 
marked spindle apparatus which appears to bring about the 
division of the chromatin with only a shght disturbance of 
its arrangement. So also in both instances the substance of 
the spindle apparatus is absorbed in the protoplasm and not 
enclosed in the reformed nuclei. 
Fig. 9 shows a stage in this division process, and also 
fig. 10 in which the kinetonucleus has divided into four 
already, and both trophonuclei are in the act of undergoing 
the second division. 
The kinetonucleus, however, shows a considerable differ- 
ence from the conditions obtaining in T. raie. 
In T. raizw the kinetonucleus became greatly elongated, 
and then divided transversely, the products of division often 
remaining connected by a red staining band. In T. vittate 
the kinetonucleus when dividing splits through longitudi- 
nally. Sometimes the split starts at one end of the kineto- 
nucleus, but takes a considerable time before being com- 
pleted, and it may thus present a horseshoe shape. The 
