No. i.] STUDIES UPON HYDROMEDUSAE. 41 



IV. Medusae. 



Experiments upon Medusae were restricted to Goniononns 

 vertcns, being the only species available in sufficient numbers, 

 and capable of adaptation to the artificial condition necessitated 

 by the nature of the work. This Medusa is found in great 

 numbers, though only in a limited locality adjacent to the 

 Marine Laboratory, and lives readily for several days, or even 

 weeks, in table aquaria, if reasonable precautions be taken to 

 keep the water fresh and supply suitable food. 



While the experiments were quite extensive and various, 

 aiming at first to ascertain the trend of resultants, no attempt 

 will be made in this connection to describe them in any con- 



FIG. 7. FIG. 8. 



siderable detail, but rather to call attention to a few of the 

 more conspicuous of them, and to indicate something of their 

 probable significance. 



Fig. 7 will afford a good idea of the general features of the 

 Medusa with the entire margin of the bell and its organs ex- 

 cised, preparatory to any contact experiments. 



In Fig. 8 are shown two Medusae from which portions have 

 been removed, the larger part of each being brought into con- 

 tact and retained by the bristle, br., passing through the body. 

 In some instances two or three bristles were passed through 

 in different planes, thus giving greater stability of contact. 



Parts of various sizes and from different regions were simi- 

 larly grafted, and with usually similar results. The time 

 required for union differed greatly in experiments conducted 

 under exactly the same conditions and care. In some cases 

 complete union had taken place within twenty-four hours, 

 while in others it only occurred after several days. It should 

 be noted, however, that when once coalescence had begun it 

 usually went forward with comparatively great rapidity. 



