THE INBORN POTENTIALITY OF THE CHILD 311 



generally enough to account for mental degeneracy ? Mental 

 energy is mainly used up in the exercise of will-power and 

 attention in acquiring knowledge and making new adaptations 

 to environment and controlling and regulating the instincts 

 and desires to the best advantage of the individual in the 

 struggle for existence in the social life. Now a healthy mind 

 can only exist in a healthy body, and the proper storage of 

 mind-energy and its liberation, as well as recuperation neces- 

 sary for a well-balanced mind, are largely dependent upon an 

 inherited good and virile constitution : whereas the higher 

 functions of the mind on the side of feeling, viz. imagination 

 and the affective nature, are specifically inherited, and more 

 dependent upon inborn variation from the normal average 

 mind. 



I have not time to discuss Galton's Law of Ancestral In- 

 heritance nor Mendel's Law ; I will only say in respect to 

 Galton's Law that it only applies to the average inheritance of 

 masses of people and not to the individual, and this was clearly 

 recognised by Galton himself, for he says : " Though one half 

 of every child may be said to be derived from either parent, yet 

 he may receive a heritage from a distant progenitor that neither 

 of his parents possessed as personal characteristics." Again, 

 speaking of particulate inheritance he remarks : " All living 

 beings are individuals in one aspect, composite in another. We 

 seem to inherit, bit by bit, this element from one progenitor, that 

 from another; in the process of transmission by inheritance, 

 elements derived from the same ancestor are apt to appear in 

 large groups, just as if they had clung together in the pre- 

 embryonic stage, as perhaps they did." They form what is well 

 expressed by the word " traits " — traits of feature and character. 

 The offspring of parents possess a mosaic of inheritance 

 bearing usually a more or less similarity, yet the mosaics of 

 characters, whether bodily or mental, are not in any way 

 identical except in the case of identical twins. Probably nothing 

 has shown more conclusively the dominant influence of heredity 

 on character than Galton's inquiries on the history of twins. 

 He found that similar twins living in a different environment 

 nevertheless remained similar in temperament and character, 

 while dissimilar twins brought up and living in the same 

 environment remained dissimilar. These dissimilar twins, 

 however, were the product of two separate ova, whereas 



