8 ZOOPHYTES. 



On April 3, a hydra was found in each of three original cells se- 

 lected for observation ; all of the palest grey, approaching transparence, 

 and provided with 20 or 22 tentacula. The yellow nucleus was almost 

 entirely dissipated, and from one end a thickish projection rose vertically, 

 or somewhat inclining, as is the case, at various degrees ; fig. 12. — Hydra a ; 

 cell b, c ; prominence b ; fig. 13. Such is always the aspect of the original 

 Flustra under slight modifications ; figs. 14, 15, 16, 17, 18, 19. 



As the prominence advanced, a cell had formed on the inner surface, 

 whence a second hydra, resembling its elder companion in parts and pro- 

 perties, protruded on the 9th of April. But their reciprocal position was 

 at variance with the structure of the adult Flustra, for the second issuing 

 at right angles to the first, overhung its fellow ; fig. 20. 



Many second hydrse were exhibited in like manner from second cells 

 on April 11. — While the first or original cell gained no horizontal acces- 

 sions, as might have been expected. But on the 13th, those of almost all 

 the latter, that is, the original hydrse of the nascent Flustra?, were dead ; 

 the sole of twenty-four nascent specimens, all under observation in the 

 same vessel, became soon after thin and transparent, the central nucleus 

 gradually vanishing away ; figs. 21, 22, 23, 24. 



Nevertheless, the vertical prominence still advanced, and while the 

 second hydra survived, a third was generated in a week, from a new cell 

 formed above it. This third animal had come to maturity in about twelve or 

 thirteen days after the evolution of the second, as the second had matured 

 in nine days after the evolution of the first ; fig. 25.— Some were vacant 

 of both first and second. 



This projection was recognised as the leaf of the Flustra. On 

 April 23, several exhibited two hydra, which, independently of the common 

 tentacular action, exercised a general percussion to right and left. The 

 habits of animals frequently prove a useful guide to the identity of species. 

 The upper edge of the leaf had advanced still higher on April 25 ; 

 and on May 4, it was evidently broadening ; a third cell, collateral with 

 the second, had formed, which was the fourth in order of time, including 

 the sole. The tallest specimen might be two lines high on May 1 7. 



In eight days, many of the hydrae had perished, though the lowest on 



