No. r.] RECENT EXPERIMENTS OX REGENERATION. 29 



experiments did I observe that apparent paralysis resulting 

 from the excision of the marginal nervous system which he 

 found so striking. However, the fact that his work was done 

 chiefly upon Scyphomedusae, while Gonionemus apparently 

 belongs to the Hydromedusae, may sufficiently account for the 

 difference. While in my experiments there seemed to be a 

 sort of shock induced by extensive mutilations, it was, how- 

 ever, in no case of any considerable duration or effect upon the 

 specimens. 



With these simple results as an index of possibilities a 

 considerable number of medusae were secured and a series of 

 systematic excisions and mutilations was begun. The following 

 synopsis will serve to indicate the scope and character of the 

 experiments, though in most respects the record must be 

 regarded as of the nature of a preliminary report, since the 

 histological investigations to determine the deeper results upon 

 the tissues are not yet sufficiently complete to be presented, 

 and, moreover, some of the primary experiments need verifica- 

 tion under other conditions than were then possible, or than 

 the time at my disposal after they were undertaken was 

 sufficient to complete. In view of the interest and signifi- 

 cance of the work in its relations to current discussions, it 

 has seemed advisable to give publicity to the facts thus far 

 established, reserving to a later time further details upon the 

 subject which may come from more extensive and critical 

 experimentation. 



Gonionemus vertens is a medusa of very interesting habits, 

 and of a form and size well adapted to the work undertaken. 

 It may not be amiss in this connection to record the fact 

 that, so far as published records of its distribution are known, 

 it had not, prior to the summer of 1895, been known on the 

 Atlantic coast. I am informed by Prof. C. C. Nutting that 

 during the summer of 1896 he found evidence at Newport of 

 its occurrence there, but at what time I could not learn. 



In Fig. i is shown in a somewhat diagrammatic form the 

 more characteristic features of the medusa. In size it varies 

 considerably, owing probably more to age than any other cause, 

 averaging from one to two centimeters in marginal diameter. 



