ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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in the third the basals were completely ankylosed. The stem must 
have been 26 to 27 in. long, the arms about 8 in. ; the height of the 
calyx to the interradials is 7/16 in. 
Ccelenterata. 
Development of Scyphostoma of Cotylorhiza, Aurelia, and 
Chrysaora.* — Prof. C. Claus deals with the developmental history of 
the three just-mentioned forms of Scyphomedusse. In some important 
points Prof. Claus confirms the results of Goette, but in others he 
disagrees with him. 
He finds that in Cotylorhiza embryonic development proceeds as far 
as the swarming Gastrula-stage within the egg-membrane. There is no 
irregular immigration of ectodermal cells into the blastula-cavity, but, 
as A. Kowalevsky has already described, the Gastrula is formed by 
invagination. Intermediate stages are presented by Aurelia between 
this mode and the ingrowth of a solid cell-mass which only later acquires 
a central cavity such as is seen in Chrysaora. The young Scyphostoma 
forms the proboscis at a very early stage ; this organ is developed from 
the ectodermal invagination in such a way that the internal lining of the 
proboscis is permanently ectodermal. Some of the organs described 
by Goette are not developed either in Cotylorhiza or in Chrysaora. 
In contradistinction to the Hydroid Polyps the young Scyphopolyp 
is characterized not only by the ectodermal nature of the lining of the 
proboscis, but by the appearance of four diverticula on the oral portion 
of the gastric cavity, which gives rise to the tentacles, as well as by the 
alternating rudiments of tseniolae. In Cotylorhiza the taenioles remain 
rudiments, situated below the oral disc, and do not extend as longitu- 
dinal ridges over the whole length of the gastric space. The four septal 
muscles do not arise as in the Anthozoa, but as ingrowths of ectodermal 
cell-growths at the peristome, and they have only a secondary relation to the 
taeniolae. The so-called septal funnels are cavities in the upper portion of 
these ectodermal growths, which may be continued into the septal muscles ; 
in Cotylorhiza , however, they are not developed. They disappear on the 
conversion of the Scyphostoma-disc into the Ephyra. The develop- 
ment of the tentacles from the four-armed to the sixteen-armed form is 
irregular and essentially the same as that already described by the 
author. The sixteen- armed Scyphostoma appears as the normal form, 
although in Aurelia and other genera the number of tentacles, before 
the appearance of strobilation, may be as much as 24 or 32. 
The conversion of the polyp-like tetrameral Scyphostoma into the 
octomeral Scyphomedusa commences with the formation of the circular 
series, of the lobed and intermediate pouches in the periphery of the same. 
The sensory knobs arise at the base of the eight radial tentacles. 
Prof. Claus is of opinion that reproduction by strobilation is a form of 
alternation of generation. 
Hydra turned inside out.t — Prof. A. Weismann vindicates 
Ischikawa’s experiments against Nussbaum’s criticisms. "When a Hydra 
is turned inside out and fixed by a bristle, it gradually rights itself. 
* Arbeit. Zool. Inst. Wien, ix. (1890) pp. 85-128 (3 pis.), 
f Arch. f. Mikr. Anat., xxxvi. (1890) pp. 627-38 (8 figs.). 
