TUBULARIA. 33 



From the result of these and other experiments, it is evident that the 

 elements of the future hydra, regenerated on a stalk, do not belong to the 

 hydra which has come to maturity, but that they reside at some distance 

 from that summit destined to bear them in their perfect state. Farther, 

 it is undoubted that their evolution and maturity depend on the presence 

 of a certain portion of the pith. 



I doubt not that skilful physiologists may rear some interesting 

 theories on the result of experiments proving that reproductions, exceed- 

 ing the number apparently allotted by nature in her usual course, can be 

 obtained artificially. Neither will the consequence of protracted inter- 

 vals be overlooked. 



From previous observations it is shown, that seven complete and one 

 abortive hydra were borne successively in 395 days by a single specimen, 

 which let us now denominate A, selected originally on November 22. — 

 PI. IV. figs. 7, 8, 9. 



The lower half which is to be denominated B, becoming very foul, 

 was cut off on the I7th of March following. In 50 days an abortive bul- 

 bous reproduction rose from the summit of this half. After 131 days 

 more a head burst on September 11. from the summit, which had reddened 

 for a long time ; but it decayed next day without complete evolution, 

 though the neck extended three lines and the tentacula were unfolding. 

 This last generation from the summit of B had occupied 297 days in at- 

 taining that degree of maturity, so long having elapsed from the time when 

 the original stem A, then comprehending B, was cut over near the root 

 on November 22. of the preceding year. This same last evolution was 

 succeeded in 40 days by another head, with about 22 tentacula somewhat 

 distorted and decaying on the second day, from a larger neck than its 

 precursor. The next, issuing in seven or eight days from the vacant sum- 

 mit, though subsisting but a single day, was suflflciently symmetrical with 

 25 tentacula. Its successor, also with 25 tentacula, several of their extre- 

 mities being mutilated, unfolded on the 11th day, and decayed in four, 

 after affording a satisfactory delineation. — PL IV. fig. 10. This was fol- 

 lowed by one in three weeks, still more evanescent, bursting with 25 ten- 

 tacula on the 5th of November, and decaying on the 6th. The last proved 



VOL. I. E 



