No. i.] 



STUDIES UPON HYDROMEDUSAE. 



43 



FIG 12. 



the surfaces, but after a few hours the specimens would almost 

 invariably have drawn apart by some sort of creeping move- 

 ments, probably aided in part by the prehensile character of 

 the manubrium, and usually one or both finally extracting the 

 bristle entirely. I am not able to suggest any satisfactory 

 explanation of the negative character 

 of this experiment. Whether regen- 

 erative tissue is wanting on this area, 

 or whether some intrinsic repugnance 

 to such fusion be the cause or occa- 

 sion, or whether some cause wholly 

 undetected was present, seems a 

 matter of doubt. There would seem 

 to be no a priori reason why this particular experiment should 

 not find as ready a response as those already described. The 

 inverted position could hardly be assigned, for specimens in 

 similarly inverted aspects readily united by the margins, as 

 indicated in Fig. 12. 



In Figs. 13-16 is shown a phenomenon which appeared in 

 connection with the series of experiments quite incidentally, 



and of which I shall undertake no 

 particular explanation, and yet which 

 is one of the most novel and interest- 

 ing of the entire series. 



In certain aboral grafts, similar to 

 those already described in Fig. 10, a 

 single specimen was found with the 

 bell somewhat evaginated, as in Fig. 

 13. During the following days, July 

 27 and 28, it passed successively 

 through the phases represented in 

 Figs. 14, 15, and 16, becoming per- 

 manently united in the completely 

 evaginated form of Fig. 16, in which condition it continued 

 to live and even take particles of food, though it showed no 

 evidences of growth, beyond a distension of the gastric pouch 

 due to the engulfed food. Finally, on August 3 the speci- 

 men died during the very sultry night, and was found the 



FIG. 13. 



FIG. 14. 



FIG. 15. 



FIG. 16. 



