HARGITT: PENNARIA TIARELLA AND TUBULARIA CROCEA. 181] 
Before much growth has taken place, the spireme undergoes a 
further change, the chromatin thread taking on the form of a number 
of loops (Figs. 31, 32, 33), which, from the first, have a definite polar 
arrangement; the attached portion of the loops being apparently 
fastened to the nuclear membrane near a common point, the opposite 
ends being always closely approximated to the opposite wall of the 
nuclear membrane, though never attached to it. It is not always 
possible, however, to demonstrate this condition, since the loops are 
often long, and extend more than half way around the inner surface 
of the nucleus. When a number of them cross one another there 
results such a complicated figure that the polar arrangement, if it 
exists, is entirely masked, the nucleus apparently containing a long 
complex spireme. ‘There is little doubt that such a polar arrangement 
regularly constitutes a stage in the odgenesis of Tubularia crocea. 
This seems to correspond to the synapsis found in so many other 
animals, and described by several authors for coelenterates. None of 
these authors, however, mentions the polar arrangement of the spireme. 
I could not determine definitely the number of loops present, though 
in the few that could be counted there seemed to be from nine to eleven. 
The further changes of this spireme can be determined only in part. 
The polar arrangement seems to be lost after a short time and does 
not appear again during the oégenesis, so far as I could find. Some 
preparations (Figs. 34, 38) seem to give evidence of a splitting or 
doubling of the threads composing the loops, but as this appearance 
has been clearly seen in only a few cases, it may be purely accidental. 
It would be difficult to conceive that a split condition was represented 
in Figure 37, which shows a stage of about the same age as that of 
Figure 38. The spireme continues to get finer and more delicate and 
also more complex in arrangement, the thread taking on a granular 
appearance, as shown in Figures 34 and 38. ‘This change to a granular 
condition continues to such an extent that, in the nearly mature egg, 
the germinative vesicle shows, besides a nucleolus, only a mass of 
granules arranged in a very extensive though delicate reticulum, 
extending throughout the nucleus (Figs. 39-46). As the reticulum 
is colored by plasma stains more intensely than by nuclear dyes, there 
results the appearance so characteristic of the germinative vesicle of 
Coelenterata and some other groups, in which the chromatin is very 
finely divided and diffused. That the chromatin is present in the 
reticulum and not in the nucleolus, will be made clear in the following 
description of the changes which the nucleolus undergoes. ‘This 
extreme diffusion of chromatin is not always equally marked in differ- 
