210 BUNTING. [Vou. IX. 
from this layer and are bounded by the bell nucleus. Thus: 
«En fait, chaque ceuf n’est un contact avec la lame testiculaire 
que cette partie agrandie de sa surface qui s’appliquait contre 
la lamelle hyaline, quand il était encore simple cellule ectoder- 
mique. Par toute le reste de leur surface les ceufs voisins et 
les cellules de endoderm regéneré.”’ It is to be noted that 
in Van Beneden’s observations he looked upon Hydractinia as 
having been formerly hermaphroditic, and that the bell nucleus 
was in the female gonophore a degenerated sexual organ. 
In Pl. I, Fig. 6, we have a distal portion of the gonophore 
shown, in which the external ectoderm layer forms a direct 
union with the endoderm of the spadix. I have never seen 
this appearance but once ; it may occur more frequently, how- 
ever, as it is a rare chance to obtain an advanced gonophore in 
which so few ova are present, as the adult gonophores usually 
contain many ova, and thus such points could be easily hidden 
from view. 
It was impossible to demonstrate the sperm mother cells 
in either the ectoderm, or endoderm of the blastostyle. 
Weismann speaks of observing groups of nuclei in the endo- 
derm, which took a different degree of staining, and which he 
considered as the male sexual cells, but such a state of affairs 
I was never able to find. Pl. I, Figs. 3, 9, represent two sec- 
tions of a series from the same gonophore; the cells a and 0 
are evidently just cut off from the ectoderm, and are to pass in 
to help form the bell nucleus; they are more granular in 
appearance and stain more deeply than the other cells.  Unfort- 
unately I have never found karyokinetic figures in the ecto- 
derm, which would place beyond a doubt the fact that the bell 
nucleus is formed by delamination from the ectoderm. The 
nuclei of the cell d (Fig. 9) appear to have just separated, but 
it is not evident enough to base any conclusions upon. Iam 
led to believe, however, that the bell nucleus has an ecto- 
dermal origin, from the behavior of the cells @ and 6 (Figs. 
8, 9) towards stains, and from their position upon the supporting 
layer. Then, also, if we examine the ectoderm in the series of 
Figs. 8-13, all of which are drawn to the same scale, we shall 
see that this layer becomes much thinner, less granular, with 
