334 THE POPULAR SCIENCE MONTHLY 



Habit on the Welfare of the Offspring," together with a research of 

 Heron's on " The Influence of Home Environment and Defective 

 Physique on the Intelligence of School Children." These researches 

 " show clearly the small influence of environment." The author on 

 page 28 writes: 



The whole subject of the influence of environment, owing to its complexity, 

 is a fascinating one, partly because we are only just beginning to apply modern 

 statistical methods to this side of eugenics, and the results we obtain are often 

 very unexpected, perhaps we may say wholly contrary to current belief. 



That they are contrary to current belief T do not deny, but to say 

 that they are unexpected shows little grasp of the whole biological 

 question of modification or knowledge of results of earlier workers. 

 In fact it will be very surprising if any one succeeds in demonstrating 

 an important environmental control acting on psychological differences, 

 exhibited in mental and moral traits. All the evidence that we possess 

 renders it highly improbable that any of the ordinary differences in 

 human environment, such as riches or poverty, good or bad home life, 

 have more than a very slight effect in modifying these complex and 

 high organic functions the improvement of which is the hope of the 

 altruist and the reformer. Not only do the collected facts indicate 

 as much, but the reasons for the same are not difficult to understand 

 if we consider the laws of diminishing environmental control. 



Each organism, whether high or low in the scale of evolution, has 

 from the time of conception and beginning of cell-division and seg- 

 mentation onward through embryonic and post-embryonic life an 

 expected environment. In other words, it expects to develop and live 

 under conditions which are essentially similar to those which sur- 

 rounded its immediate ancestors at each stage of their career. 48 



If the expected environment is altered, then the modification which 

 will accrue will in general diminish, (1) in proportion as the change 

 from the expected is less and less in amount. This will follow as a 



48 Since writing this I have received a letter from a distinguished student 

 of heredity containing some remarks on the question of environment versus 

 inheritance. This gentleman, like so many others, does not see that although 

 a result may be due to a complexity of forces we may, nevertheless, measure 

 the relative value of the different components. I refer him, for his encourage- 

 ment, to the opening chapters of any text-book on physics where the " Laws of 

 Motion," " Parallelogram of Forces " etc., suggest helpful analogies. One illus- 

 tration which the correspondent gives may serve to make my own standpoint 

 clearer if I answer it here. He says " the question of whether nature or nurture 

 plays the greater part does not arise. As well might we ask whether the loco- 

 motive or the steam plays the greater part in transporting the train." My 

 answer is, that by all the needs of a suffering humanity or the development of 

 a rational understanding of the present, past or future of this same species, 

 Homo sapiens, the question does arise; and second that the illustration from 

 the locomotive will do as well as any other. Here, it is the locomotive, not the 



