MISCELLANEOUS. 243 



mains behind, which, instead of becoming a Medusa like the rest, is gra- 

 dually evolved as a perfect Hydra tuba, with a suitable complement of 

 tentacula. 



It seems from the preceding passages, that a hydra undergoing the 

 changes which take place in spring, was recovered from the sea affixed to 

 a large shell, a pecten, along with many others, on March 21 ; that the 

 individuals of a medusan roll generated there were advancing to maturity on 

 March 27, and that all had been liberated by the 5th of April. 



Had this medusan roll been affixed immediately to the shell, the spot 

 which it occupied would have remained bare, but the elementary, smooth, 

 fleshy bulb intercepting it, which is not dissolved like the rest, had attained 

 the general shape of a hydra on March 27, with tentacula then extending. 

 Vol. I., Plate XX. figs. 6, 7 ; its form was subsequently perfected, as seen 

 fig. 20, and progeny generated by gemmation is represented figs. 21, 22. 



We had left it there ; but considering the importance of prosecuting 

 the history of this elementary bulb still farther, I followed its progress 

 with the utmost care. 



The form being then developed as a perfect hydra, I did expect to 

 see the nature of its race displayed on return of the accustomed season, 

 especially as the gemmation of the young seemed to prove its integrity — 

 that it was quite entire in all respects. 



The faculty of perpetuating the kind seems commonly reserved by 

 nature as a test of the maturity of the parent in almost every tribe, that 

 maturity being determined in general by the age or the size of the indivi- 

 dual. 



But the Hydra tuba apparently affords a remarkable exception, in so 

 far that it is not shewn to be dependent on age or dimensions that young are 

 developed from the parent ; nor is it shewn by any authentic observation 

 at what precise period of the animal's existence the medusan roll, presum- 

 ing that to be the progeny, is generated. 



The fleshy bulb having become a hydra, its offspring amounted to 

 seven in 125 days from liberation of the Medusa, Vol. II., Plate L. fig. 1 ; 

 the young are omitted. It fed copiously, and became of a fine yellow 

 colour, and had enlarged considerably above its original dimensions ; eight 



