568 
MARGARET EORINSOX. 
unchanged. 1 look upou it merely as the casting out of 
superfluous chromatin, most probably one of the spherules 
mentioned above, which is quickly dissolved and then absorbed 
by the surrounding protoplasm (6g. o,s 2 )h.). 
In some of the cysts intermediate in age between that 
shown in fig. 5 and the pearl stage there are to be seen some 
large nuclei at least twice the size of the others. I have 
never seen these nuclei dividing, but some of them are in 
a state of degeneration. In the earlier stages all the nuclei 
divide in exactly the same way. There are not two methods 
of division as in S ty lor hy nch u s (Leger, 1903). These 
nuclei in the earlier stages seem to be not in any way 
different from their neighbours; but after having divided 
a certain number of times they divide no more, then 
degenerate and die. In the process of degeneration they 
naturally swell up a little, but their largeness in size as 
compared with the others is mainly due to their not having 
undergone so many divisions. 
It seems to me that mitotic divisions are continued right 
on until the pearl stage,” or, as Mr. Cunningham calls it, 
the “convolution stage” is reached. 
Mr. Cunningham, when he wrote his account of Kalpido- 
rhynchus, was inclined to think that he was dealing- with 
a case of isogamy. Nevertheless, he found a slight dift'erence 
between the contents of the gametocytes enclosed in one 
cyst. I, too, am convinced that there must be an inherent 
difference between the gametocytes, but in the cysts which 
I cut this difference Avas not appreciable till just before the 
pearl stage was reached. Then, while the dividing-wall 
between the two gametocytes Avas still intact, it could be 
seen that the protoplasm on one side of the Avail stained 
more deeply than that on the other, and that its mesh work 
Avas slightly, but only very slightly, finer. It could also be 
seen that the nuclei on the darker side Avere rounder, smaller, 
and darker than the others, showing a more concentrated 
chromatin. In sections through cysts at the pearl stage a 
great accentuation of these differences can be noticed. Ou 
