MEDUSA BIFIDA. 123 



hydra : the emerging of a new circle of tentacula from a smooth fleshy 

 bulb, sustaining the embryonic roll, as the former are obliterated, and 

 as the Medusse approach maturity, the evolution of this fleshy bulb as 

 a perfect hydra, along with their departure, which becomes the parent of 

 progeny by gemmation, and its permanence as an independent animal. 



Among the various questions to which the attention of naturalists 

 should be directed, is — 



1. How is the body of the hydra afifected in the earliest stages of al- 

 teration ? I rather thought that it was by progress downwards, the first ap- 

 pearance of change taking place near the circle of the original tentacula. 



2. Is it truly an alteration of the body itself, or is the change from 

 the embryonic roll being originally generated within the body, or upon the 

 disc? I found it impossible to determine, until ascertaining this fact, 

 whether the subsequent division and dissolution was that of the hydra itself, 

 or of the product generated from it or upon it. I rather thought, when 

 the most favourable view could be obtained, that the smaller end of the 

 roll, when the rest had advanced, appeared as if inserted in the hydra's 

 mouth, or where we should expect to find its mouth. 



3. How and when is the original circle of tentacula obliterated ? It 

 appeared to me, that, as the waving of the cylinder deepened, the vigour 

 and regularity of the circle I have described as consisting of 20 or 24 ten- 

 tacula, were impaired ; that they contracted and were effaced. I could 

 not discover how, if they belonged to the fleshy bulb, they were conducted 

 around the expanding Medusan lobes to the extremity. Had it been so, 

 their obliteration might have followed simple contraction, and possibly 

 they might have extended as new tentacula, for the hydra has uncommon 

 power over its parts. 



The terminating circle seems somewhat within the circle of maturing 

 MedusEe. That is, the Medusan circle is of larger diameter than the ten- 

 tacular circle. 



This latter circle seems quite unconnected with and distinct from the 

 hiffhest Medusa, whose liberation, in as far as I could discover, never pre- 

 ceded obliteration of the tentacula. I have witnessed this incident, but 

 the first Medusa escaping before me, was always free of foreign organs. 



