328 SEA-SIDE STUDIES. 



identical with the seed ; * but no one, I believe, has 

 carried this doctrine to its legitimate conclusion, namely, 

 that Generation is only a form of Growth ; because 

 every one has assumed that the union of two dissimilar 

 cells is the necessary commencement of every genera- 

 tion. Even Owen, who maintains that Gemmation is 

 closely allLed to Generation, does so because he main- 

 tains that the original unchanged cells, which resulted 

 from fecundation, form the starting-point of the bud ; 

 and that thus the bud and seed are identical, because 

 both really originate in identical cells — both really 

 issue from an original act of fecundation ; whereas these 

 pages contain abundant evidence that fecundation is by 

 no means necessary to Generation, except in the higher 

 animals ; plants, polypes, insects, and crustaceans, being 

 generated without fecundation. 



It is worthy of remark that, although the Hydra 

 propagates by eggs and by buds, it only produces two 

 or three eggs during the autumn, whereas it buds all 

 the year round. We may consider its oviparity, there- 

 fore, as an exceptional process. I believe it is one solely 

 determined bv external conditions, and that if the 

 Hydra were kept in an unvarying temperature, it would 

 never produce eggs at all, but continue budding to the 

 end of the chapter. 



All the endeavours to prove that Parthenogenesis is 

 in every case the result of mere Gemmation are power- 

 less against Owen, who denied the essential difference 

 between Gemmation and Generation, and serve to sup- 



* Wolff : Theorie von der Generation, p. 47. 



