32 ZOOPHYTES. 



fig. 19. An enlargement from the other half of the same cleft b, had ap- 

 peared also on the 1st of January, which burst as a head on the 16th; 

 fig. 20, b. But from being invested with some mucous matter it scarcely 

 expanded. No more flourish came of the former cleft a ; however, the 

 latter, b, generated a symmetrical head, with 14 tentacula, about the 13th 

 of February ; and this was succeeded by another with 19, on the 13th of 

 March. But an interval of 167 days now followed its decay, when a very 

 small head, with parts imperfectly developed, replaced it. 



Probably the number, the size, and the distribution of regenerated 

 organs will depend on the laceration or impunity of the foetus or latent 

 embryo, or on the obstacles and facilities presented for their evolution. 

 The peculiar condition of the early subject must expose it more or less to 

 injury. But it is remarkable that the originating organization of animals 

 invisible to mankind, and in such a stage of existence should be thus im- 

 paired, as proved by later increment. Where the head is much smaller, 

 and only half the wonted number of tentacula belonging to a perfect hydra 

 border the disc of one or of two regenerated, it is not unreasonable to 

 conclude that the embryonic product was cleft asunder ; that if the num- 

 bers be nearly equal it was bisected. 



A fine and florid stalk which had borne a prolific hydra was cleft 

 half an inch down on October 24. Much of the wound healed up as usual ; 

 but on November 6, a distorted disc, with 30 tentacula, of sufficient di- 

 mensions, bearing a double pouch, each having its peculiar palpi unfolded, 

 though imperfectly. Next evening, the neck, originally very stout, had 

 refined along with the rest into better proportion ; but the heads were 

 more distorted. — PI. IV. figs. 21, 22, 23, 24. This reproduction subsisted 

 only another day ; but, in a week, a single head, with 30 short stunted 

 tentacula, a pouch unusually distended, and very short palpi, rose from the 

 vacant stalk. Having burst its spath, it decayed without complete evolu- 

 tion on the day following. In nearly three months it was succeeded by a 

 new head, somewhat distorted, with about 25 irregular tentacula, which 

 decayed in three days. 



The reproduction, PI. II. fig. 12, was of similar character to the 

 preceding figures, as above described. 



