Febeuaby 3, 1911] 



SCIUNCE 



179 



it is always a good plan to do the easiest 

 things first, partly because it takes less 

 time to get results, but chiefly because the 

 easy things usually throw light on the hard 

 ones. We know that suitable changes in 

 the environment, if made at a suitable 

 time, will cause such changes in the or- 

 ganism that the next generation differs 

 from the first. It is a very difficult prob- 

 lem to determine the intermediate steps; 

 but it is a relatively simple one to deter- 

 mine what change in the second generation 

 is the result of a change in a single factor 

 of the environment. This is a problem 

 which has not been attacked by the biol- 

 ogist in any systematic fashion, and it is a 

 problem which will be greatly simplified 

 by an intelligent application of the 

 theorem of Le Chatelier. 



The view of the biologists seems to be that 

 each generation always varies spontane- 

 ously from the preceding one to a greater 

 or lesser extent, and that these variations 

 are reproduced more or less completely in 

 the succeeding generation. By the sur- 

 vival of the fittest we eventually get a 

 race which is better adapted to the local 

 conditions than the one from which we 

 started. 



The view that I have outlined is that 

 the external conditions tend to produce 

 such changes in the organism that the next 

 generation varies in such a way as to be 

 more adapted to local conditions. By the 

 survival of the fittest and by the continued 

 action of the external conditions, we 

 eventually get a race which is better 

 adapted to the local conditions than the 

 one from which we started. 



We reach the same conclusion whichever 

 way we consider the matter. The two 

 views are not mutually exclusive because it 

 is quite possible to consider the variation 

 due to the external conditions as superim- 

 posed on the spontaneous variations. If 



we are to decide between the two points of 

 view, it must be on other grounds than 

 qualitative results. To me, the phrase 

 "spontaneous variation" seems merely 

 another way of expressing our ignorance. 

 I do not believe in a variation without a 

 cause. If we go back far enough, all 

 variations must be the result of varying 

 external conditions and the real problem is 

 to show what part of any given variation 

 in any given organism is due to the effect 

 of external conditions on the preceding 

 generation and what part is due to the ef- 

 fect of external conditions on still earlier 

 generations. What we study under hered- 

 ity, as the word is usually used, is the 

 transmitted effect of varying external con- 

 ditions upon the more or less remote an- 

 cestors. 



Another objection to the biologist's 

 point of view is that it has not M'orked out 

 well practically. Being obsessed by the 

 idea of spontaneous variation, he has very 

 rarely taken the trouble to work out care- 

 fully the relation between each particular 

 factor of the external conditions and the 

 acquired characteristics of the organism 

 which has become better adapted to its sur- 

 roundings. If the biologist had had the 

 theorem of Le Chatelier as a guiding hy- 

 pothesis, he would not have made this mis- 

 take and he would often have done better 

 and more careful work. 



I have tried to show that the theorem of 

 Le Chatelier is a universal law and that it 

 is consequently of great value in enabling 

 us to correlate old facts and to discover 

 new ones. 



Wilder D. Bancroft 



COBNELL UNIVEKSITT 



THE SEVENTEENTH INTERNATIONAL CON- 

 GRESS OF AMERICANISTS 

 The second session of the seventeenth In- 

 ternational Congress of Americanists was held 



