CHAPTER VI 



TRANSMISSION OF PHYSICAL AND MENTAL 

 CHARACTERISTICS 



Physical heredity extends far beyond those 

 family likenesses so apparent in feature, stature, 

 strength, colour of the hair and eyes, complexion, 

 and so forth. There is not a fibre or a nerve of our 

 bodies, however small or insignificant, or a faculty 

 dependent thereon, which is not transmissible. The 

 size and shape of the head, bones and teeth, the 

 circulatory system, the muscles and nerves, the 

 digestive apparatus, the richness or poverty of the 

 blood, diseases of the "constitutional" order, a 

 tendency to early baldness or gray hair, longevity 

 and shortness of life, long and short sight, and 

 malformations, are all matters with w^iich heredity 

 is concerned. Probably all these characteristics are 

 subject not only to direct transmission, but to trans- 



