182 
U. M. WOODCOCK. 
It is undouLtedly in tlie above-described promitotic manner 
that the unecpuil division of the karyosoiue takes place in the 
young forms of Karyolysus; for I have found two or three 
examples which show very clearly the still persistent centro- 
desmose between the two halves (fig. 20). This fibril 
stretches apparently across the general nuclear mass; but it 
may really lie outside it, i. e. above or below; I do not feel 
sure upon the point. The smaller daughter-karj’osome result- 
ing from the division always comes to lie at the opposite side 
of the nucleus to the other, larger one (figs. 24, 2G). This 
smaller, secondary karyosome, however, soon becomes incor- 
porated with the general nuclear material; either it is 
distinguishable as a rather larger and more prominent grain, 
or else, probably having undergone further subdivision, it can 
be no longer distinguished from the rest of the chromatic 
substance. Now and again, it may be mentioned, in such a 
nucleus a small, but sharp and well-defined granule is seen in 
the centre; this may very likely be the centriole (fig. 40). 
The nucleus has by this time changed its position and passed 
to one end of the body of the parasite. In the majority, if 
not in most cases, it leaves behind it the larger half of the 
karyosome, wdiich resulted, i. e., from the original promitotic 
division ; this remains near the middle of the body, the nucleus 
simply moving away from it. hy this change in the nuclear 
position occurs I cannot say ; it might be supposed, perhaps, 
that it had some connection with the commencing develop- 
ment of the U-form of the parasite, but the bending of the 
cytoplasm sometimes takes place at the end opposite to that 
to which the nucleus travels. AVhatever the reason, this 
movement occurs, 1 should say, very rapidly, for I have not 
succeeded in finding an individual which show's the nucleus 
caught in the act, as it were, halfway between the end of the 
body and the stationary karyosome. This latter element 
thus left behind takes no further share in the nuclear 
development, and appears to be entirely discarded. As 
already indicated, it alters considerably in staining pro- 
perties and indefiniteness of outline; it gradually becomes 
