440 
MONTGOMERY. 
[Vol. XV. 
Germinal vesicles , nucleoli. — In this genus the earliest egg 
stages are more favorable for study than in the other metane- 
merteans. In the connective-tissue nuclei from which the ger¬ 
minal vesicles are directly derived (with no intervening cell 
generations) no nucleoli are present, though this conclusion was 
possible only after much careful observation. These small 
nuclei (Figs. 213, 217, 218, 220, 228, C. T. N.) are character¬ 
ized by a relatively thick membrane and by chromatin which is 
usually granular in distribution, but which may sometimes 
occur in the form of granular fibers. These chromatin masses 
might at. first sight be confounded with nucleoli, but their small 
size and irregular contours show that they are true chromatin 
granules. Further, when these nuclei are stained by the 
Ehrlich-Biondi method, these fibers and granules always stain 
with methylen green (chromatin reaction) and not a single one 
stains with fuchsine (which invariably stains any true nucleoli). 
Accordingly, what could not be finally proved for the other 
metanemerteans, though all observations pointed to its being 
the case there, could be definitely settled for Stichostemma> 
namely, that these connective-tissue cells contain no nucleoli ; 
in other words, nucleoli first arise in the definite germinal 
vesicles. 
Before proceeding to the description of the egg cells it may 
be noted that not all the undifferentiated connective-tissue 
cells within the gonad become germinal vesicles. I have previ¬ 
ously (’ 95 ) shown that the young gonad is a cell syncytium in 
which numerous nuclei are unevenly scattered through a mass of 
cytoplasm, but cell boundaries cannot be seen (Figs. 217 and 218). 
A few of these nuclei increase in size and eventually become 
germinal vesicles, and the latter reach maturity not simultane¬ 
ously but in succession, so that no gonad contains more than one 
large ovum at a given time. The numerous other nuclei which 
do not become thus differentiated degenerate, and their sub¬ 
stance is eventually absorbed by the gradually increasing mass of 
cytoplasm of one of the growing egg cells. These regressive 
processes are as follows (Fig. 218, C. T. N.) : the nuclei 
increase a little in size, but become much clearer in appearance, 
i.e., the relative amount of their chromatin appears to decrease ; 
