242 ZOOPHYTES. 



My own remarks, though deduced from practical experience, are 

 offered with considerable reluctance, nor can I feel otherwise than diffi- 

 dent, from conscious inability to decide whether the animals were in a 

 permanent or only in a transient state. 



The metamorphoses undergone, especially by marine products, are so 

 extraordinary, that, without having beheld them under their different 

 phases, due reserve ought to guide us, both in regard to what may be seen 

 by ourselves, and as to what may be affirmed as having been seen by 

 others. 



Recurring to the earlier portion of this work, it is there explained, 

 that a peculiar roll appears on the disc of the Hydra tuba in the course of 

 spring, which, advancing from an imperfect state originally, at length re- 

 solves into a number of minute Medusae. 



Though hundreds of these minute Medusae, such as above described, 

 have been thus bred in my possession, and have committed themselves to 

 the surrounding element, as the roll pendent from the hydra gradually 

 dissolved, the survivance of none of the whole exceeded sixty days; nor, 

 in the course of that time, did the smallest sensible change ensue, either 

 by organic increment, or the evolution of additional parts. They perished 

 in the precise state wherein they were first recognised. 



I have not heard that any other naturalist has been more fortunate, — 

 that he has succeeded in preserving those component portions of the me- 

 dusan roll under uninterrupted observation until some farther ©volution, 

 alteration, and increment, admitted their identification with adult animals. 

 If this has been actually done, my ignorance of it must plead an 

 apology for protracting the narrative. I have observed it affirmed, it is 

 true, that older and larger Medusa? are the adults of the younger and 

 smaller tribe now referred to. But I have not seen any demonstration of 

 the facts, possibly owing to my very limited sphere of information. 



Recurring to the subject discussed in Vol. I. p. 127, and in relative 

 passages, it will be remembered, that after an embryonic roll generated 

 on the disc of the hydra advances, all the tentacula disappear, and that the 

 dissolution of the roll succeeds by the successive liberation of minute Me- 

 dusae composing it : that a smooth, fleshy bulb or fragment, nevertheless re- 



