INTESTINAL TEYPANOPLASMAS OF FISHES. 
187 
membrane splits. One blepliaroplast^ attaclied to its portion 
of the split undulating membrane, and carrying probably two 
of the free flagella, moves away from its original position. 
At the same time the anterior end of the kinetonucleus splits, 
and it would appear from the later stages of division that this 
part is carried over in connection with the migrating 
blepharoplast to a position on the opposite side of the 
animal. The only thing that is abundantly clear in this 
division of the kinetonucleus is that no trace of a mitotic figure 
can be found, and it is hard to see what part a mitotic 
figure could play in such a division. During division the 
chromatin in the trophonucleus becomes condensed within 
the nuclear membrane into a dumb-bell-shaped structure. In 
the later stages the dividing trophonuclei move apart, so that 
the handle of the dumb-bell becomes much elongated, and 
still persists at a stage (PL 9, fig. 20) at which the cytoplasm 
at the anterior end is already showing distinct signs of 
division. 
In the case of Trypanoplasmoides I have also found 
rounded forms, which apparently result in the structure 
shown in PL 9, fig. 21. I have not any evidence to decide 
whether this is a stage of the process of encystation. I do 
not propose in this paper entering into a discussion as to the 
origin and meaning of the curious form which has been 
named by Alexeieff, Trichomonas legeri, as at present I 
have no evidence as to its final fate. It would appear, how- 
ever, from the preparations that I have examined that two 
Trypanoplasmoides conjugate, and the trophonuclei fuse 
together. At this point possibly the kinetonuclei break 
down, although on this point I am rather doubtful. A 
great part of the chromatin is thrown out into the cytoplasm 
of the conjugating individuals, and the animal finally comes 
to possess the curious elongated nucleus with its tiny karyo- 
some characteristic of this form. I am not at all clear as to 
the behaviour of the flagella during this process, but the 
undulating membrane seems to be absorbed at a relatively 
early stage of the process, and I believe this is also true of 
