M (J R A L 1 T V 



lion between parts of the orj^^anism and the outer world. Varia- 

 bility or adaptability is not, therefore, a special orj^anic function, 

 but depends on the material, physico-chemical process of 



nutrition. 



I have developed this conception of adaptation in the 

 tenth chapter of the History of Creation. 



The nature of the adaptation and its relation to varia- 

 tion are often conceived in diflercnt ways from that 

 I have defined. Quite recently Ludwig Plate has re- 

 stricted the idea, and understood by adaptation only 

 variations that are useful to the organism. He severely 

 criticises my broader definition, and calls it "a palpable 

 error," suggesting that I only retain it because 1 am not 

 open to conviction. If I wanted to return this grave 

 charge, I might point to Plate's one-sided and perverse 

 treatment of my biogenetic law. Instead of doing this I 

 will only observe that I think the restriction of adapta- 

 tion to useful variations is untenable and misleading. 

 There are in the life of man and of other organisms 

 thousands of habits and instincts that are not useful, but 

 either indifferent or injurious to the organism, yet cer- 

 tainly come under the head of adaptation, are main- 

 tained by heredity, and modify the form. We find 

 adaptations of all sorts — partly useful, partly indifferent, 

 partly injurious (the result of education, training, dis- 

 tortion, etc.) — in the life of man. and the domestic 

 animals and plants. I need only refer to the influence 

 of fashion and the school. Even the origin of the use- 

 less (and often injurious) rudimentary organs depends on 

 adaptation. 



Habit is a second nature, says an old proverb. This 

 is a profound truth, the full ap])reciation of which came 

 to us through Lamarck's theory of descent. The forma- 

 tion of a habit consists in the frequent repetition of one 

 physiological act, and so is in j)rinciplc reducible to 

 cumulative or functional adaptation. Through this 



415 



