MENTAL HEliEDlTY llj 



CHAPTER XIV 



MENTAL HLKEDITY 



This concluding chapter is merely a brief adden- 

 dum, added for the sake of formal completeness. 

 The facts of mental heredity are dealt with at leni^th 

 in the volume on psychology. Thanks to the epoch- 

 making work of Herbert Spencer, the psychology 

 of to-day is essentially an evolutionary or genetic 

 science. The leading problems of psychology are 

 problems in mental inheritance. From the point of 

 vie^v ot biology proper, we recognise the unques- 

 tionable inheritance, in all animals that possess a 

 nervous system, of a nervous organisation which is 

 intimately correlated with the facts of mind and 

 consciousness. Nearly all the questions discussed 

 in the preceding pages have an immediate bearing 

 on psychology. One of the chief problems of the 

 psychologist, for instance, is as to the existence of 

 innate ideas, or ideas or " modes of consciousness," 

 or "forms of thought," which are independent of 

 experience. The question arises whether these 

 ideas are independent of individual experience but 

 dependent upon racial experience. This doetrine 

 would appear to imply something very like the 

 inheritance of acquired characters. 



All that must be insisted on here, however, is that 

 the physical characters of the brain antl spinal cord 

 and system of nerves are subject to the same laws 

 of inheritance as the physical characters of the 

 limbs, or the skeleton, or the internal organs. Pro- 



