NOTES ON SPOEOZOA III. 
211 
occupying the same excentric or peripheral situation iu the 
nucleus which is occupied iu other forms (e.g. Karyolysus, 
Adelea”) by the karyosome. I suggest that this element 
represents the plastin basis of an ancestral karyosome, the 
chromatin which it originally stored having become now 
(permanently) distributed through the general nuclear 
material in the form of numerous large conspicuous grains.^ 
In this connection an observation made by Reichenow is 
significant. He found that in the young growing schizont, 
chromatic substance is regularly eliminated from the nucleus 
and cast out of the cell-body of the parasite, i. e. a precisely 
similar occurrence to that seen in Karyolysus and 
Barrouxia sp. Reichenow is uncertain whether it is the 
nucleolus Binnenkorper ”) which is thus got rid of; hut, as 
he himself points out, the fact that the nucleolus is always very 
faintly stained, while the expelled element stains on the con- 
trary deeply and is manifestly chromatic in origin, is against 
this view. Moreover, I may point 'out that iu slightly older 
schizonts again, the nucleolus is still present in the nucleus 
(c f. Reichenow’s figs. 73-75). Hence it is more probable 
that this eliminated chromatic substance is derived from the 
general nuclear chromatin. As this process here doubtless 
has the same object as the corresponding one in other 
parasites, the inference is that the chromatin which in other 
cases is stored up in the karyosome is in H. stepanovi 
incorporated with the rest of the chromatic material of the 
nucleus, the plastin basis of the karyosome alone remaining. 
On this explanation, and having regard to the views I have 
expressed above, it is readily understandable why the 
nucleolus does not divide, with the formation of a “ Hautel- 
Figur,” a fact which appears to have puzzled Reichenow. 
There is no need for a division-centre to be present in the 
nucleolus because it no longer possesses the chromatin of a 
* So prominent are these grains and apparently in ceidain phases 
usually of a fairly constant number (i. e. within limits) that Reichenow 
is inclined to regard them as definite units comparable to chromo- 
somes. 
