xv the relation of facts to theories 325 



Criticism of Other Theories 



Theories which attempt to minimise Natural 

 Selection seem always sooner or later to assume 

 an inheritance of acquired characters, and of this 

 there is little evidence. They also assume that 

 environmental influences have a direct effect upon 

 the organism, and of this Weismann's work has 

 made many doubtful. Or rather, Weismann has 

 endeavoured to prove that those apparently direct 

 responses to environmental stimuli which are facts 

 of experience, can be interpreted also as the result 

 of adaptation, and this, if proved, is fatal to 

 theories like that of Simroth. It is, however, 

 to be noticed that in the case of the artificially 

 produced variations in the colours of butterflies, 

 competent entomologists {e.g. Garbowski) are of 

 opinion that the new colours have little or no phylo- 

 genetic importance, and that as yet it is impossible 

 to correctly interpret them. There is, indeed, much 

 evidence to show that in the case of butterflies the 

 colours can be influenced by their surroundings in a 

 way of which the mechanism is at present unknown. 



Much of this is, however, apart from our main 

 object, which is merely to show that in spite of the 

 fluency with which so many people talk of the 

 meaning of colour in organisms, the subject is as in- 

 complete on the theoretical as on the physiological 

 side. It seems reasonable to believe that the two 

 deficiencies are related, and that a little more 

 physiology will arm the theorists with better 

 weapons. In the meantime, we cannot end a book on 

 Colour more fitly than by an appeal for more facts. 



