Masterpieces of Science 



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 in 

 a much greater degree than the other pairs which 

 inhabit the same country, for all will have been 

 continually blended through free intercrossing. 

 By considering the embryological structure of 

 man — the homologies [parallels] which he pre- 

 sents 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 pro- 

 per place in the zoological series. We thus 

 learn that man is descended from a hairy, tailed 

 quadruped, probably arboreal«in its habits [living 

 on or among trees] and an inhabitant 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 monkeys. The Quadrumana and all the 

 higher mammals are probably derived from an 

 ancient marsupial animal [usually provided with 

 a pouch for the reception and nourishment of 

 the young, as in the case of the kangaroo] and 

 this through a long line of diversified forms, 

 from some reptile-like or 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 Verte- 

 brata must have been an aquatic animal, pro- 

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