170 THE CONTROL OF LIFE 



evolution has not occurred (as far as we understand) 

 by adding on additional pieces as wings might be added 

 to a house ; there is unification .at the beginning of 

 each new life. And again it must be recognised that 

 each kind of creature is specific, itself and no other. A 

 frog has at one stage in its tadpole Hfe a two-chambered 

 fish-Hke heart, a fish-hke type of circulation, and old- 

 fashioned gills Uke the external gills of some ancient 

 fishes, but it is an amphibian all the same from beginning 

 to end. The recapitulation doctrine requires careful 

 handhng. 



But we are not here interested in embryos, is there 

 recapitulation in juvenile Hfe ? The answer must be 

 cautious. Our inheritance is made up of ancestral 

 contributions, including a few very ancient instinctive 

 predispositions — of self-preservation, nutrition, sex, 

 and the herd-instinct — but the non-human elements 

 in these instincts have been gradually sifted out. And 

 the instinctive under-current has to operate in most 

 cases through an upper current of consciously con- 

 trolled life. Yet, those who give an attentive ear may 

 still catch reverberating in the recesses of their being 

 the echoes of a very distant past. 



§ 5. Childhood : Its Playing and Schooling 



What comes out of the egg of a snake is a miniature 

 snake, which usually goes about its business forth- 

 with. But in many mammals there is, after the chap- 

 ter spent in darkness and the period of infantile de- 



