5a THE CONTBOL OF LIFE 



using the convenient phrase that a parent transmits 

 gifts and blemishes to his offspring. For parents are 

 not so much the immediate producers of children as 

 the custodians or trustees of germ-cells which develop 

 into children. 



It is natural to ask : What makes up our inheritance ? 

 and modern investigation has begun to answer the 

 question, (a) Within the circle of the normal, we all 

 start with a stock of old-established human characters 

 which exhibit little essential change from generation 

 to generation. Thus every child has a certain structure 

 of heart or lung, of brain or eye, which is characteristic 

 of mankind, which is not departed from in any essential 

 way except on rare occasions. Many of these funda- 

 mental characters have their counterparts in all ordinary 

 backboned animals, every type having them, but having 

 them in some distinctive form. Thus part of our inherit- 

 ance includes a backbone, a structural item of incon- 

 ceivable antiquity ; but what we have is not only a 

 backbone, it is a mammal's backbone. More than that, 

 it is a Primate backbone ; more precisely still, it is a 

 humanoid backbone — ^that and nought else. Or again, 

 while men differ greatly from one another in wits, every 

 child has as part of its inheritance a brain, and this is 

 not merely a Vertebrate's brain, it is a Mammal's brain, 

 a Placental Mammal's brain, a Primate brain, a human- 

 oid brain, and in all ordinary cases a brain characteristic 

 of the ' modern man type.' There are between man and 

 man great differences in the relative size and weight 

 of the brain in proportion to the body ; there are 



