^6 THE EVOLUTION OF MAN. 



these infinitely various groups of phenomena in these dif- 

 ferent departments becomes explicable and comprehensible 

 solely through the theory of descent, therefore this theory 

 of evolution must be regarded as an extensive inductive 

 law. If we now really apply this inductive law, and with 

 its help seek to discover the descent of individual organic 

 species, we must necessarily form phylogenetic hypotheses, 

 which are of an essentially deductive nature, and which are 

 inferences from the general theory of -descent back to indi- 

 vidual particular cases. These special deductive conclusions 

 are, however, in accordance with the inexorable laws of 

 Logic, as justifiable, as necessary, and as indispensable in 

 our department of knowledge as the general inductive 

 conclusions of which the whole theory of evolution is 

 formed. The doctrine of the animal parent-forms of man- 

 kind is Sbho a special deductive law of this kind, which is 

 the logical conclusion from the general inductive law of the 

 theory of descent.-^^ 



As is noAV very generally acknowledged, both by the 

 adherents of and the opponents of the theory of descent, 

 the choice, in the matter of the origin of the human race, 

 lies between two radically different assumptions : We must 

 either accustom ourselves to the idea that all the various 

 species of animals and plants, Man also included, ori- 

 ginated independently of each other by the supernatural 

 process of a divine " creation," which as such is entirely 

 removed from the sphere of scientific observation — or we 

 are compelled to accept the theory of descent in its entiret}^ 

 and trace the human race, equally with the various animal 

 and plant species, from an entirely simple primseval parent- 

 form. Between these two assumptions there is no third 



