288 SEA-SIDE STUDIES. 



who brought liis own quota of important facts. In this 

 work, * a flasli of liglit suddenly revealed the connection in 

 which many isolated paradoxes stood to each other : a 

 theoiy was proposed, which, although really nothing but a 

 metaphorical expression of the already known facts, was very 

 widely accepted as a perfect solution of the difficulty. 



In 1849, Professor Owen published his two lectui-es on 

 Parthenogenesis, in which, re-stating the results of his inves- 

 tigations into the reproduction of Aphides (1843), he pro- 

 pounded a theory as a substitute for the metaphor of Steen- 

 strup, and one which up to this time is the sole theory not open 

 to the charge of being a merely verbal explanation. In the 

 same year, Victor Cams published a small work \ containing 

 some new observations, and an ingenious classification. 



In 1851 Leuckart published an essay J to prove that alter- 

 nate generation was shnply metamorphosis plus asexual gen- 

 eration — an unhappy explanation, since the peculiarity of me- 

 tamorphosis is that the lai'va becomes a perfect insect, whereas 

 the Polype never becomes a Medusa, it only produces it ; the 

 •wingless Aphis never becomes a perfect insect ; moreover, the 

 phrase "plus asexual generation " conceals the real difficulty. 



In 1853, Van Beneden, to whom we owe so many impor- 

 tant contributions, published a work § in which he modestly 

 contents himself with stating the phenomena, classing ani- 



• Oil (he Alternation of Qenerations. Translated for the Eay Society by Mr 

 George Bosk, 184G. 



+ Zur nUliem Kennlnisi des General ionswechsels, 1849. 



J SlEBOLD M KoLLiKEU's ZeiUschrift, iii. p. 170. He repeats the idea in his 

 work on Comparative Anatomj', written in conjunction with Bergmanu. 



§ La Oiniration aUernante et la Digiii&Sf, ISiiS. 



