306 SEA-SIDE STUDIES. 



asexual generation — an unhappy explanation, since the 

 peculiarity of metamorphosis is that the larva 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 

 important contributions, published a work * in which 

 he modestly contents himself "vvith stating the pheno- 

 mena, classing animals under two heads, monogenetic 

 or sexual, and digenetic, i. e. reproducing themselves by 

 sexual and asexual methods. 



In 1855 M. Quatrefages published four articles 

 in the Revue des Deux MoJides entitled Les Meta- 

 mo7yhoses, in which he re\4ewed the state of the 

 question, criticised the theories, and propoimded one 

 of his own. 



In 1856 another brilliant flash of light came from 

 Germany. Von Siebold published a work f containing 

 some starthng facts, and such as, in my opinion, will 

 serve to dissipate all the clouds from the question. He 

 ofiered no theory himself; and in the only remark which 

 directly touches our subject, he desnes to lay " parti- 

 cular stress upon the distinction between the alternation 

 of generations and Parthenogenesis." In spite of this, 

 I must think that the two are one, and that his facts 

 convincingly prove them to be so. For the present. 



)3. 



* La Generation alternante et la Digenese, 18oS 

 + On true Parthenogenesis in Moths and Bees. Translated by J. W. 

 Dallas, 1857. 



