6 HEREDITY AND INHERITANCE 



we seek to distinguish what is due to " Nature " from what is 

 due to " Nurture." 



Heredity and Inheritance defined. — In regard to property 

 there is a clear distinction between the heir and the estate which 

 he inherits, but at the beginning of an individual life we cannot 

 biologically draw any such distinction. The organism and its 

 inheritance are, to begin with, one and the same. It is easy to 

 make this clear. Every living creature arises from a parent 

 or from parents more or less like itself ; this reproductive or 

 genetic relation has a visible material basis in the germinal 

 matter (usually egg-cell and sperm-cell) liberated from the 

 parental body or bodies ; by inheritance we mean all the qualities 

 or characters which have their initial seat, their physical basis, 

 in the fertilised egg-cell ; the expression of this inheritance in 

 development results in the organism. Thus, heredity is no 

 entity, no force, no principle, but a convenient term for the 

 genetic relation between successive generations, and inheritance 

 includes all that the organism is or has to start with in virtue of its 

 hereditary relation. 



Nature and Nurture.— The fertilised egg-cell implicitly con- 

 tains, in some way which we cannot image, the potentiality 

 of a living creature, — a tree, a daisy, a horse, a man. If this 

 rudiment is to be realised there must be an appropriate 

 environment, supplying food and oxygen and liberating-stimuli 

 of many kinds. Surrounding influences — maternal or external — 

 begin to play upon the developing germ, and without these 

 influences the inheritance could not be expressed, the potentiali- 

 ties could not be realised. Thus, the organic inheritance implies 

 an environment, apart from which it means nothing and can 

 achieve nothing. Indeed, it is only by an abstraction that we 

 can separate any living creature from an environment in which 

 it can live. Life implies persistent action and reaction between 

 1 organism and environment. 



But while the inherited nature and its possibilities of action 



