34 THEORY OF EVOLUTION 



was no evidence opposed to his ingenious the- 

 ory, based as it was on an appeal to the ac- 

 knowledged facts of improvement that take 

 place in the organs of an individual through 

 their own functioning ( a fact that is as obvious 

 and remarkable today as in the time of La- 

 marck), yet now there is evidence as to 

 whether the effects of use and disuse are inher- 

 ited, and this evidence is not in accord with 

 Lamarck's doctrine. 



THE UNFOLDING PRINCIPLE 



Ndgeli and Bateson 



I have ventured to put down as one of the 

 four great historical explanations, under the 

 heading of the unfolding principle, a conception 

 that has taken protean forms. At one extreme 

 it is little more than a mystic sentiment to the 

 effect that evolution is the result of an inner 

 driving force or principle which goes under 

 many names such as Bildungstrieb, nisus for- 

 mativus, vital force, and orthogenesis. Evolu- 

 tionary thought is replete with variants of this 

 idea, often naively expressed, sometimes uncon- 

 sciously implied. Evolution once meant, in 



