Reproduction in the Hydra viridis. 283 



h\ question was misrepresented by Laurent so lately as in 1 842.* 

 But very recently the fact of the occasional bisexual genera- 

 tion of the common polypes has been fully confirmed and de- 

 scribed by V. Sieboldt in his text-book of comparative ana- 

 tomy. 



I have not been able to refer to the original of the second 

 notice regarding this subject, by Ehrenberg, which was pub- 

 lished in the MittheiL aus d. Verhandl. d, Gesellschaft Naturf. 

 Freunde in Berlin, 1838, p. H ; and I only became acquainted 

 with his and V. Siebold's observations a considerable time after 

 1 had observed carefully the two bodies, and distinguished their 

 nature. The naturalists I have referred to appear to have had 

 under observation principally the Hydra fusca and /T. auran- 

 iiaca ; and V. Siebold only once makes mention of having seen 

 the ova in the Hydra viridis ; and it is on this last species, the 

 organization of which is the simplest of the tribe, that my 

 observations have been made. 



It appears to me of some importance, that the fact of the 

 co-existence of the two generative elements in an animal of the 

 extremely simple structure presented by the Hydra, should 

 receive every confirmation ; and the interest created by the 

 variety of modes in which that animal is capable of being re- 

 produced, may, perhaps, warrant my detaining the Society a 

 few minutes with a short notice of the phenomena to which I 

 have referred. 



Through the greater part of the year the common polype 

 is reproduced by gemmation, or by the growth of buds upon 

 the parent stock ; and occasionally, but much more rarely, by 

 cleavage, or in the fissiparous mode ; the division being some- 

 times longitudinal, at others transverse. These processes have 

 been described so fully by Trembley and others, and are so 

 familiar to most naturalists, that it seems unnecessary to dwell 

 upon them here. Suffice it to say, that, in so far as we are 



* Frori«'p8 Neue Noti«en, p. 104. 



t Lehrhuch der Vergleich. Anatomkf Von V. Siebold und Stannius, B. i. 

 p, 46. 



