POLYPES PRODUCING JELLY-FISH. 281 



could not distinguisli from a seaweed, producing scores of 

 Jelly-fish ; and these Jelly-fish, if their days were spared, 

 would in due time produce Polypes. Imagine a lily pro- 

 ducing a butterfly, and the butterfly in turn producing a 

 lily, and you would scarcely invent a marvel greater than 

 this production of Medusae was to its first discoverers. Nay, 

 the marvel must go further still ; the lily must first pro- 

 duce a whole bed of lilies like its own fair self, before giving 

 birth to the butterfly ; and this butterfly must separate it- 

 self into a crowd of butterflies before giving birth to the 

 lily : when you have thus added marvel upon marvel, you 

 will be ready to listen without scepticism to the phenomenon 

 known as the " alternation of generations," since Steenstrup 

 so baptised it. Others have given it other names : Owen 

 calls it "Parthenogenesis;" Van Beneden, "Digenesis;" 

 Victor Carus, "Neomelie ;" and Quatrefages, "Geneagenesis." 

 But while difiering about the name, and the explanation of 

 the phenomena, there is no difference as to the phenomena 

 themselves. I will ask the reader's attention to a succinct 

 exposition of the various facts and theories connected with 

 this interesting subject ; premising that I have not only 

 verified the capital observations on which the marvel rests, 

 but have some new facts to bring forward which must 

 materially modify the current conceptions. 



Harvey's celebrated aphorism, 07nne viviim ex ovo (every 

 living being issues from an egg), was a premature gener- 

 alisation, and has for some years past been known to be so. 

 Many animals issue not from an egg, but du'cctly from the 



substance of the parent's body, by a process analogous to 



2 A 



