696 THE DESCENT OF MAN. 



conditions of life, though in different degrees, would have 

 survived in greater numbers than the less well-fitted. The 



Erocess would have been like that followed by man, when 

 e does not intentionally select particular individuals, but 

 breeds from all the superior individuals and neglects the 

 inferior. He thus slowly but surely modifies his stock and 

 unconsciously forms a new strain. So with respect to 

 modifications acquired independently of selection, and due 

 to variations arising from the nature of the organism and 

 the action of the surrounding conditions, or from changed 

 habits of life, no single pair will have been modified much 

 more than the other pairs inhabiting the same country, for 

 all will have been continually blended through free inter- 

 crossing. 



By considering the embryological structure of man the 

 homologies which he presents with the lower animals the 

 rudiments which he retains and the reversions to which 

 he is liable, we can partly recall in imagination the former 

 condition of our early progenitors; and can approximately 

 place them in their proper place in the zoological series. 

 We thus learn that man is descended from a hairy, tailed 

 quadruped, probably arboreal in its habits and an inhabi- 

 tant of the Old World. This creature, if its whole 

 structure had been examined by a naturalist, would have 

 been classed among the Quadrumana, as surely as the still 

 more ancient progenitor of the Old and New World mon- 

 keys. The Quadrumana and all the higher mammals are 

 probably derived from an ancient marsupial animal and 

 this through a long line of diversified forms, from some 

 amphibian-like creature, and this again from some fish-like 

 animal. In the dim obscurity of the past we can see that 

 the early progenitor of all the Vertebrata must have been an 

 aquatic animal, provided with branchiae, with the two sexes 

 united in the same individual, and with the most important 

 organs of the body (such as the brain and heart) imper- 

 fectly or not at all developed. This animal seems to have 

 been more like the larvae of the existing marine Ascidians 

 than any other known form. 



The high standard of our intellectual powers and moral dis- 

 position is the greatest difficulty which presents itself, after 

 we have been driven to this conclusion on the origin of 

 man. But every one who admits the principle of evolution 



