The Theory of Natural Selection. 255 



adapted to browsing on high foliage. And so in the 

 cases of other animals, Lamarck believed that the 

 adaptation of their forms to their habits could be ex- 

 plained by this simple hypothesis that the habits 

 created the forms, through the effects of use and dis- 

 use, coupled with heredity. 



Such is what is ordinarily known as Lamarck's 

 theory of evolution. We may as well remember, 

 however, that it really constitutes only one part of his 

 theory ; for besides this hypothesis of the cumulative 

 inheritance of functionally-produced modifications to 

 which we may add the inherited effects of any direct 

 action exercised by surrounding conditions of life, 

 Lamarck believed in some transcendental principle 

 tending to produce gradual improvement in pre-de- 

 termined lines of advance. Therefore it would really 

 be more correct to designate the former hypothesis by 

 the name either of Erasmus Darwin, or, still better, of 

 Herbert Spencer. Nevertheless, in order to avoid con- 

 fusion, I will follow established custom, and subse- 

 quently speak of this hypothesis as the Lamarckian 

 hypothesis understanding, however, that in employ- 

 ing this designation I am not referring to any part 

 or factor of Lamarck's general theory of evolution 

 other than the one which has just been described 

 namely, the hypothesis of the cumulative transmission 

 of functionally-produced, or otherwise "acquired," 

 modifications. 



This, then, was the earliest hypothesis touching the 

 causes of organic evolution. But we may at once 

 perceive that it is insufficient to explain all that stands 

 to be explained. In the first place, it refers in chief 

 part only to the higher animals, which are actuated to 



