36 



be similarly transmitted. Just, in fact, as the qualities of 

 a plant are transmitted in its seed, so, not only the physical, 

 but the mental characteristics of the organism are trans- 

 mitted from parents to their children. Moreover, the brain, 

 which I have denominated the organ of mind, is, as Dr. 

 Mortimer Granville says, " composed of nerve cells and 

 fibres, the latter serving to communicate, and the former 

 being endowed with the power of receiving and recording 

 the impressions produced by external objects through the 

 senses, together with such conceptions of impression as are- 

 evolved in the course of the operations of thought. No 

 intellectual function is performed, or sensation experienced 

 or imagined in short, nothing takes place in the mind, or 

 within the range of the perceptive faculties without a 

 physical change in the minute structure or organism of the 

 brain, and the physical changes so produced are the records 

 which form the bases of memory. . . . More than this, 

 as family likeness is perpetuated from parent to child, the 

 brain, with its characteristic properties, will be reproduced, 

 at least, so far as to give an inherited bias to the mind of 

 posterity. It is in this way mental constitutions are trans- 

 mitted, and tendencies to the commission of crime or the 

 practice of virtues, special powers of work or particular in- 

 competencies and neuroses are transmitted also." We thus 

 see that the embryonic vesicle contains not only the forma- 

 tive capacity of reproducing the physiological likeness of the 

 parents, but the potentiality of developing their modes of 

 thought and action their character, their powers of 

 reasoning, their intelligence. 



I shall now pass briefly in review those psychological 

 phenomena 1 which are subject to heredity, and which, in 



1 Summarised mainly from Ribot. 



