212 BUNTING. [VoL. IX. 
Van Beneden has shown in Hydractinia that the external 
ectoderm folds in to form the bell nucleus. I, therefore, studied 
my sections with great care; after which several hundred 
blastostyles were examined from surface views, made possible 
by means of clearing with clove oil. The lesson which this 
investigation seemed repeatedly to teach was, that a few cells 
were cut off from the ectoderm at a certain position, and these 
cells gradually increased to form the double-layered bell nucleus 
in which a cavity never existed, the layers always remaining 
closely applied to one another. 
FORMATION OF THE BELL NucLEUS OF PODOCORYNE, AND 
ORIGIN OF SEx-CELLS. 
The blastostyle of Podocoryne is, as has been mentioned, 
much smaller than the nourishing polyps, although still bearing a 
marked resemblance to them. According to Weismann a germi- 
nal zone does not exist, but rather a “ Knospungszone,” which 
is found at about the same area. The origin of the ova from 
the endoderm of the young blastostyle before the appearance 
of the medusa buds, was not seen, as was observed by Varenne. 
I finally came to the conclusion of Weismann, that possibly 
Varenne had mistaken for ova the darkly staining cells which 
are frequently met with in the endoderm; these are with- 
out doubt glands, as they are also present in the nourishing 
polyp. 
The medusa-bud in Podocoryne appears first as an out- 
pushing of both ectoderm and endoderm. In the female bud 
represented in Pl. I, Fig. 14, we observe ova of different ages 
lying in the endoderm. As the bud progresses in its develop- 
ment, we find the ova in the endoderm of the manubrium. 
When a later stage has been reached, they migrate from the 
endoderm to the ectoderm, as is clearly shown in PI. I, Fig. 16, 
in which a, 6 are in process of passing through, while c, d are 
in the ectoderm, and ¢ still in the endoderm. A small drawing 
of the entire bud is given in Fig. 17, to show the orientation 
of the manubrium. In the adult state the ova are always 
to be found in the ectoderm. In one case an ovum was 
