138 



A number of these little bodies were kept for several days in 

 jars, and were seen by Mr. Desor, as well as by Drs. Bowditch, 

 Cabot, and Abbot, and several other persons, to contract violently 

 until the different cups became detached from the mass and 

 were seen swimming about as free Jelly-fishes, of the species 

 hitherto known as Ephyra. The base remained and preserved 

 its polyp-like form ; being of a white and sometimes of a light 

 orange color, whilst the bunch of young Medusse was pink. 



The observations of Mr. Desor confirm entirely the views 

 taken by Sir John Dalyell, as to the nature of this basis or trunk 

 of the larva, which is described by him under the name of 

 Hydra tuba. It is a genuine polyp, bearing all the characters of 

 the true Hydra, so that it seems difficult to separate it from that 

 genus. 



But this polyp by no means transforms itself into a Me- 

 dusa, either entirely, as M. Sars supposes, or in part, as is 

 supposed by Sir John Dalyell. It remains a genuine polyp during 

 its whole life, and buds in a manner similar to that of Syncoryjie, 

 Tubularia, and- other Polyps, but with the difference that the bud, 

 instead of growing from the side or from the axis of the polyp, 

 grows from within the circle of the tentacles, in the form of a red 

 hernia, which soon elongates, becomes wrinkled transversely as 

 it grows, and finally transforms itself into as many small Me- 

 dusse as there are transverse divisions of the bud. 



The circumstance that this bud when fully developed is larger 

 than the polyp itself, has probably prevented the above-mentioned 

 eminent naturalists from understanding fully its true meaning; and 

 led them to consider erroneously the whole process as a trans- 

 formation or metamorphosis of the polyp itself, while it is really 

 nothing but the growth of a bud out of the body of the polyp; 

 which is found unaltered after it has fallen off, with just the same 

 form and outline as before ; just as the Syncoryne remains 

 unaltered and continues its polyp life, when its offspring, the 

 Oceania^ has fallen off. [See Page 133.] Mr Desor said 

 that neither he nor any of the gentlemen who watched these 

 larvse saw any indication of tentacles at the top of the bud. 

 The tentacles of the polyp remained unaltered at the base of the 

 bud, where one would expect to find them, as the bud grows 

 from within, and seems to undergo no change either in form or 



