250 Chas. W. and G. T. Hargitt. 



acles retain their irritability, and active response, contracting 

 after stimulus qu'te as usual, though less vigorously or promptly. 

 This is more evident as resorption approached completion. This 

 would seem to be what might naturally be expected. It seems, 

 therefore, that it may be said that the reduction or atrophy of 

 the tentacles is due primarily to direct resorption unaccompanied 

 by distinct evidences of degenerative changes. There was evi- 

 dence to suggest that in the process of tentacle resorption.those of 

 the primary series, i.e., the perradial and interradial, were first 

 involved, followed by those of the later series, but at irregular 

 intervals. However, there was much variation in this respect, 

 each tentacle behaving more or less in an independent or indi- 

 vidual manner. 



Except for certain theoretical considerations we might dismiss 

 the subject at this point. As is well known, it has long been a 

 rather current and general assumption that in Scyphozoa the 

 rhopalia, or so-called sense organs, are metamorphosed tentacles. 

 So wide spread is this view that one can hardly consult any of the 

 current text-books of zoology in which it is not asserted without 

 qualification or doubt. As an example the following citation 

 from Hertwig's Lehrbuch, (Kingsley's translation, p. 246), may 

 be given as a fair illustration. "Instead of a nerve ring there 

 are eight nerve centers connected with the sensory pedicels. 

 Each of these pedicels is a modified tentacle with an entodermal 

 axis and an outer layer of ectoderm." 



In connection with experiments on regeneration in Scyphozoa 

 (1904), the senior author had occasion to express serious doubts 

 as to the validity of this assumption. Later study and research 

 has tended to confirm the doubt, and has strongly impelled the 

 conclusion that there is no genetic relation whatsoever between 

 these organs. Critical study of the actual process of tentacle 

 resorption shows it to be purely physiological, quite as much so as 

 that of such processes generally. It would be the height of ab- 

 surdity to suggest that the urostyle of the frog's skeleton might 

 be a metamorphosed polywog tail ; but hardly more so than the 

 one here under review ! 



