The Development of Scyphomedussr. 249 



The Ephyra 



Touching this phase occasion will be taken to mention chiefly 

 one feature, that relating to metamorphosis from the strobila. 

 One of the first general signs of this change is that of the 

 apparent atrophy of the scyphistomal tentacles. Concerning 

 this feature Agassiz (op. cit.), says ''at this time the wreath 

 of tentacles which crowns these bodies is cast off, and during the 

 fair days of that season, in the month of March or early April, 

 the saucer-like disks of the strobila begin to separate." As a 

 matter of fact the tentacles are not ''cast off" at all, but are re- 

 sorbed, as is well known. Various accounts have been given as to 

 just how this takes place. According to Bigelow (1900), it is by 

 a process of degeneration. According to Friedemann (1902), it is 

 by a complication of modes, namely, a strangulation of the base 

 of the tentacle, partly through the crumpling and atrophy of the 

 tissues, with the cooperation of the phagocyte cdls. "Die 

 Riickbildung der Tentakeln erfolgt theils nach vorhergehender 

 Einschntirung an der Basis und nachfolgendem Abwerfen, theils 

 durch Schrumpfung und Atrophie des Gewebes mit Hilfe von 

 Phagocytaren Zellen." 



These accounts do not seem to be confirmed, except in a lim- 

 ited degree, in the case of Cyanea. There is not apparent at any 

 time the degenerative aspects described by Bigelow. Nor has 

 the basal constriction referred to by Friedemann been observed. 

 That something of phagocytosis may be involved seems altogether 

 probable, though definite evidence of the actual operation of 

 such phagocytic cells has not been observed. In one case actually 

 followed from beginning to end it was found that some twenty- 

 four hours were involved in the process. As is therefore evident, 

 it proceeds slowly, a fact further suggesting the operation of 

 resorption, due in part perhaps to phagocytosis, and perhaps in 

 part to the direct influence of contiguous tissues. The latter would 

 seem to be the more important and active of the two. That 

 there is no marked evidence of distinctively degenerative pro- 

 cesses involved may be inferred from the fact that for some time 

 after resorption is under way, indeed till far advanced, the tent- 



