The Development of Scyphomedusse. 223 



obtain ova in earl}" maturation and cleavage. This it was not 

 possible to do in any quantity, egg-laying appearing to be a more 

 or less continuous process during all times of day, and for a number 

 of days in succession. Another feature will make this more evi- 

 dent. In both Aurelia and Cj^anea the eggs are not definitely 

 discharged from the female; but after dehiscense from the ovary 

 into the gastric cavity, where apparently fertilization takes place, 

 they are ' nursed' in pocket-like folds of the oral arms for some time 

 or until they are well-developed planulse. Hence one finds on 

 attempting to collect eggs that he gets all conditions of develop- 

 ment at the same time, though in the immediate proximity of 

 the mouth there will be a preponderance of cleavage stages and 

 early blastulse. That egg-laying is not a single process, as shown 

 above, is evident in that one finds specimens with the gonads in 

 various stages of depletion. Furthermore, in a study of the his- 

 tology of the gonads one finds eggs 'in all stages of growth, a fact 

 incompatible with the assumption of the shedding of the entire 

 crop at a single time. 



The eggs, when they escape from the ovaries, have already gone 

 through the process of maturation. This would seem to take 

 place just prior to the rupture of the follicular membrane by the 

 egg, as will be shown in a later connection. 



Following the liberation of the sexual products, and in the case 

 of the females the final escape of the larva), there seems to be a 

 rather rapid decline in the vigor and activity of Aurelia and early 

 death ensues. Many specimens may be found drifting along 

 shore lines and in harbors, and, if there be wind or tide driving 

 them shoreward, they become stranded and rapidly disintegrate. 

 An examination of many such during the past summer showed that 

 in most cases such specimens were dead or dying when they came 

 ashore. The case of Cyanea seems somewhat different. This 

 medusa seems to live for considerable time after passing the spawn- 

 ing period. As stated before, the breeding season is usually in 

 spring. But it is not unusual to find many specimens during early 

 and late summer swimming freely in the usual manner. It is, 

 however, rare to find such specimens bearing genital products. 

 In many specimens collected in Casco Bay during the past summer 

 not one w^as found with gonads. 



