EMBEYONIO FISSION IN CYCLOSTOMATOUS POLYZOA. 29 



(1. c, p. 28). This account is confirmed by Haeckel (14), who 

 observed the production, in three weeks, of 60 — 80 buds, from 

 ten isolated gastrulse of Chrysaora. 



The process of larval fission or gemmation is known to be 

 even more remarkable in Aurelia (Haeckel, 1. c). Not only 

 do the gastrulse multiply, in some cases, by budding or by 

 fission, but the same processes are known to occur in the 

 Scyphostoma stage; while numerous variations are recorded 

 in the character of the strobilatioUj in the multiplication of 

 the tentacles by incomplete fission or budding, and even in the 

 number of the highly characteristic taeniolse and in that of the 

 Ephyra-lobes. 



The property of giving rise to fresh individuals, whether by 

 budding or by fission, has, in this case, become a normal 

 feature of the species ; and the process takes place even at 

 very early periods of the development, just as is the case in 

 Crisia. The striking variability in the number of the radii 

 of the immature stages in Aurelia may possibly be con- 

 nected with something in the constitution of the egg which 

 predisposes it to develop in an unusual way. 



For since the cells which are destined to give rise to a single 

 individual are not normally separated off until a late stage, 

 which varies in difi'erent individuals, the existence of a ten- 

 dency to vary in the number of individuals produced from an 

 egg might also, in all probability, make itself felt in variations 

 in a difi'erent direction. If the gastrula contains in itself the 

 power to develop into several individuals, it is hardly surpris- 

 ing that it should in some cases develop an abnormal number 

 of radii. 



Similar cases of larval budding have been recorded in other 

 Scyphomedusse. Thus Goette (12), confirming an older ob- 

 servation of Sars (1841), shows that the formation of a stolon 

 may take place (presumably in Cotylorhiza tuberculata) 

 in the lai'va which has just fixed, but which is still without 

 tentacles. Ciliated buds are also given off from the Scypho- 

 stoma of Cotylorhiza, the buds fixing^ and developing a 

 mouth after fixation. 



