The Evidence from Intellectual Differences. 255 



male shares with the female the characteristics which 

 unite them to the other barnacles, and which are due to 

 descent from a common form. The female keeps these 

 hereditary characteristics through life, while the male 

 soon loses them entirely. 



These facts seem to be sufficient to prove that the 

 specialization which we should expect to find among the 

 higher animals with separate sexes does exist, and that 

 the male organism is especially and peculiarly variable, 

 and the female organism especially and peculiarly con- 

 servative. 



Leaving this aspect of our subject for the present, let 

 us look at it from a somewhat different point of view. 

 The history of the evolution of life has not only an ob- 

 jective side, but something which may with perfect pro- 

 priety be spoken of as a subjective aspect. The progress 

 which is shown objectively as greater and greater special- 

 ization of structure, and a closer and closer adaptation 

 of the organism to the conditions of the external world, 

 has been well described by Herbert Spencer, as the in- 

 creasing delicacy, exactness, and scope of the adjustment 

 between internal and external relations. Seen in its 

 subjective aspect, each of the steps in the growth of this 

 adjustment is a recognition of a scientific law, the per- 

 ception of the permanency of a relation between external 

 phenomena ; for science is simply the recognition of the 

 order of nature. 



When a Rhizopod discriminates between the contact 

 of a large body and that of a small one, and draws in its 

 pseudopodia and shrinks into as compact a shape as 

 possible in order to escape the danger which the past 

 experience of the race has shown to be related to the 

 former sensation, or when it expands its pseudopodia in 

 order to ingulf and digest the body which has caused 



