xii.] THE GENEALOGY OF ANIMALS. 309 



I think that his method of stating the case has the in- 

 convenience of tending to leave out of sight the impor- 

 tant fact which is a cardinal point in the Darwinian 

 hypothesis that the tendency to vary, in a given 

 organism, may have nothing to do with the external 

 conditions to which that individual organism is exposed, 

 but may depend wholly upon internal conditions. No 

 one, I imagine, would dream of seeking in the direct 

 influence of the external conditions of his life for the 

 cause of the development of the sixth finger and toe 

 in the famous Maltese. 



I conceive that both hereditary transmission and adap- 

 tation need to be analysed into their constituent condi- 

 tions by the further application of the doctrine of the 

 Struggle for Existence. It is a probable hypothesis, that 

 what the world is to organisms in general, each organism 

 is to the molecules of which it is composed. Multitudes 

 of these, having diverse tendencies, are competing with 

 one another for opportunity to exist and multiply ; and 

 the organism, as a whole, is as much the product of the 

 molecules which are victorious as the Fauna, or Flora, 

 of a country is the product of the victorious organic 

 beings in it. 



On this hypothesis, hereditary transmission is the 

 result of the victory of particular molecules contained in 

 the impregnated germ. Adaptation to- conditions is the 

 result of the favouring of the multiplication of those 

 molecules whose organizing tendencies are most in har- 

 mony with such conditions. In this view of the matter, 

 conditions are not actively productive, but are passively 

 permissive ; they do not cause variation in any given 

 direction, but they permit and favour a tendency in that 

 direction which already exists. 



It is true that, in the long run, the origin of the 

 organic molecules themselves, and of their tendencies, is 



