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OTTO C. GLASER 
metamorphosis, and had completed that process in an aquarium 
in which it Hved for over two months. During the early part of 
this period, a few hydromedusae were present, but these soon 
died out, and the eolid passed the greater portion of its captivity in 
the absence of coelenterate food. Serial sections, upon careful 
examination, since repeated, revealed nothing that could be iden- 
tified as a nematocyst, either in the liver or in the cnidophores. 
Even under natural conditions cases of this kind may occur. 
Like Krembzow, I have found, on several occasions, eolids prac- 
tically devoid of nematocysts, as well as barren cnidophores among 
many heavily charged. These facts are easily understood if the 
nematocysts are derived from coelenterates, but on the contrary 
view they appear as abnormalities without known explanation. 
The experiment of hatching and rearing the young in aquaria 
free of coelenterates, would give an unequivocal answer could it 
be carried out. Many difficulties however, present themselves, 
most important of which are the fatal attacks of the infusorians 
inevitably introduced with the food and water. Cuenot ('07), 
nevertheless was able to m.ake tests of a strictly analogous nature. 
By clipping the cerata and allowing regeneration to occur in the 
absence of coelenterates, he produced eolids with appendages 
partly free of nettles. The failure to regenerate cerata entirely 
devoid of nematocysts was due to the presence of capsules in 
other portions of the digestive tract, in the lumen of the liver as 
well as of its diverticula, and engulfed even in the liver cells 
themselves. Many of these nettles found their way into the re- 
generating cnidophores, but even so, not in sufficient number to 
destroy the great contrast between the restored and the ampu- 
tated appendages. This slight uncertainty in Cuenot 's results 
could be eliminated entirely by starving the animals for four 
or five days before operating. 
The transfer of nematocysts 
Cuenot has said that the best evidence of the derivation of 
- solidian nettles is their history. This has been most carefully 
worked out by Grosvenor, and certain points in it have been 
