THE NATURE OF REPRODUCTION. 



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seen in company with each other, and were known to reproduce by 

 sexual congress. Not to mention some extreme instances of this 

 among insects and other invertebrate animals, it is sufficient to refer 

 to the cock and the hen, the lion and the lioness, the buck and the doe. 

 In man, the distinction shows itself in the mental constitution, the dis- 

 position, habits, and pursuits of the two sexes, as well as in the general 

 conformation of the body, and its external appearance. 



The special details of the generative process depend on the struc- 

 ture of the male and female organs, the manner in which the sexual 

 products are formed and discharged, their union in the act of fecunda- 

 tion, and the changes which take place in the development of the 

 embryo. 



