118 DARWINISM AND HUMAN LIFE 



waters which requires only time and experience 

 to produce what is new. 



MODIFICATIONS, OR ACQUIRED CHARACTERS. 

 We must now ask a very important question. Are 

 there no other raw materials of evolution besides 

 those inborn changes which we call variations and 

 mutations, which we trace back to more or less 

 mysterious processes occurring in the germinal 

 material ? It is well known that our bodies suffer 

 change according to what we do or do not do, and 

 according to climate and food, and so forth. Does 

 this sort of change not furnish part of the raw 

 material of evolution ? 



Among the observed differences which mark 

 man from man, or trout from trout, or buttercup 

 from buttercup, there are many to which we can- 

 not apply the word "variation." For, apart 

 from constitutional or inborn changes, there are 

 differences which are impressed upon the body 

 in the course of life by influences from without, 

 such as sun-burning in man or colour in trout ; or 

 by use and disuse, such as callosities on the fingers. 

 These do indeed presuppose a constitution capable 

 of being changed, but we can relate each to some 

 definite influence, either of function or of environ- 

 ment, which has brought about a structural change 

 transcending the limits of organic elasticity. We 

 call these modifications, and though they may be 

 of much importance to the individuals possessing 

 them, they are not known to be of any direct 

 importance in the evolution of the race, for the 

 simple reason that there is no convincing evi- 

 dence that they can be transmitted. Here the 

 Lamarckians entirely dissent ; but they have still 

 to prove their case. 



