REGENERATIVE POTENCIES OF DISSOCIATED CELLS. 377 



developed within the next two or three days, and conformed 

 exactly to the phases of the growth of an embryonic specimen. 

 It should be emphasized in this connection that in the rate of 

 growth in these specimens, as in the entire regenerative process, 

 there was great individual difference. Apparently this was 

 dependent upon the state of vitality of the underlying organiza- 

 tion. For example, it was found that development was slower, 

 and the resulting polyps smaller when arising from small cell 

 aggregates, and in cases where there had been an excessive 

 stolonization prior to polyp formation. In the one case it would 

 seem as if the store of energy was small to begin with, and in the 

 second that it had been depleted by excessive stolon formation. 



The young polyps continued to live for several weeks, much 

 longer than would have seemed probable when the highly 

 artificial conditions, and the very limited food supply are taken 

 into consideration. During the course of the experiments more 

 than a dozen of these polyps of Podocoryne were reared to func- 

 tional maturity and many others to such stage as to leave no 

 trace of doubt as to the validity of the results. 



Let it be remarked here that in this species all the material 

 was in the asexual condition, that is, there were polyps only, no 

 signs whatever of medusae, which are the sexual stage in the life 

 cycle of Podocoryne. Other experiments go to show that so far 

 as use of material of asexual or mixed condition no difference as 

 to regenerative potency could be distinguished. In Eudendrium 

 where the medusa stage is absent, and where one finds sex cells 

 in various stages of growth, the experiments were apparently 

 not thereby influenced at all. Indeed, in those cases in which 

 egg cells were present they took no part whatever in later re- 

 generative activity, either degenerating or being absorbed as 

 yolk material. 



Eudendrium. — In experiments upon Eudendrium two species 

 were used, E. rameum, and E. racemosum, both very common at 

 Naples. Methods of treatment were the same as in the case 

 already described. The promptness with which these hydroids 

 had responded in the numerous previous experiments by the 

 writer^ and others in regeneration and regulation led me to 



1 BioL Bull., VoL I., p. 35- 



