THE PROTOZOA PARASITIC IN ARCHOTERMOPSIS WROUGHTONI 257 
intact, and can be seen throughout the whole process of 
division. This is contrary to the statement made by Imms. 
Directly after its formation the spireme is loosely packed 
together, but subsequently its component parts become more 
closely aggregated. Finally, it breaks up into a number 
of long threads, which separate one from the other to form 
4 < a 4 aval ml r i~< 
the so-called chromosomes (‘Text-figs. 5 and 7), and the clear 
Space once more arises. These threads, however, do not 
appear to split longitudinally, nor can they be seen to be 
lying together in pairs previous to their separation. During 
the process just described the nucleus elongates, becoming 
Text-Fic. 5. TEXT-FIG. 6; 
Nucleus in which the spireme Dividing nucleus with the ‘ chromo- 
is breaking into individual somes ’ passing to each pole. Spindle 
threads. x950; S.A., H.I.H. fibres or paradesmose not present, 
x 1,250; S.A. (D.J.), H.1.H. 
oval in shape, with the poles somewhat pointed. The long 
chromosome-like threads now separate into approximately two 
equal groups, one of which passes to either pole of the elongate 
nucleus (Text-fig. 6). Further elongation occurs, and at the 
same time the threads begin to aggregate to form a compact 
mass, which finally breaks up into irregular chromatin masses 
to form the daughter nuclei (Pl. 10, fig. 7). Finally, the 
membrane constricts, dividing in the middle. 
This process must take place rapidly, for it is common to find 
bi-nucleate animals and animals in which the division phase 
is being initiated, but it is exceedingly rare to encounter the 
intermediate stages. 
