68 SCIENCE AND PHILOSOPHY OF THE ORGANISM 



depend on the " historical basis of reacting " : in other terms, 

 the elements of the individualised acting effect are derived 

 from this basis. 



What the theoretical consequences of this relation are 

 will be shown hereafter ; at present the minute analysis of 

 the correspondence between the individualised stimulus and 

 the individualised effect concerned in action is to be our 

 chief problem. As every problem of a complicated nature 

 is easier understood when at first demonstrated in a concrete 

 instance, I prefer to begin our discussion with a concrete 

 fact. It will be a fact very familiar indeed to all of you, 

 for it is the great advantage in this department of biology 

 dealing with action, that the facts are generally matter of 

 common knowledge, whilst in morphogenesis even the most 

 simple facts of a merely descriptive character have to be 

 first explained to laymen in order to make them available 

 for theoretical discussion. 



We all experience a hundred times a day what a con- 

 versation between two human beings is. Let us try to 

 analyse what a conversation would mean from the point of 

 view taken by natural science. Two friends meet in the 

 street, and one of them, A, says to the other, B, " my brother 

 is seriously ill." There will be a very specific effect caused 

 in B by the stimulus that went out from A. Let us 

 imagine that the brother is in America : B then would talk 



o 



about the difficulty of his coming home, or of visiting him, 

 and very many other things, all of them of a very definite 

 and specific character. But what would have happened if 

 instead of the word " brother " the word " mother r> had been 

 used ? Certainly something very different, and certainly 

 something very specific also. The mother may be living in 



