Masterpieces of Science 



importance, have been gained through sexual 

 selection. 



No doubt man, as well as every other animal, 

 presents structures, which, as far as we can judge 

 with our little knowledge, are not now of any 

 service to him, nor to have been so during any 

 former period of his existence, either in relation 

 to his general conditions of life, or of one sex 

 to the other. Such structures cannot be accounted 

 for by any form of selection, or by the inherited 

 effects of the use and disuse of parts. We know, 

 however, that many strange and strongly 

 marked peculiarities of structure occasionally 

 appear in our domesticated productions, and 

 if the unknown causes which produce them 

 were to act more uniformly, they would prob- 

 ably become common to all the individuals of 

 the species. We may hope hereafter to under- 

 stand something about the causes of such 

 occasional modifications, especially through the 

 study of monstrosities; hence, the labours of 

 experimentalists, such as those of M. Camille 

 Dareste, are full of promise for the future. In 

 general we can only say that the cause of each 

 slight variation and of each monstrosity lies 

 much more in the constitution of the organism 

 than in the nature of the surrounding conditions; 

 though new and changed conditions certainly 

 play an important part in exciting organic 

 changes of many kinds. 



Through the means just specified, aided per- 

 haps by others as yet undiscovered, man has 

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