NATURAL RESISTANCE 179 



At first glance these conclusions may appear to be 

 at variance with the results of the author's experiments 

 concerning the breeding of animals. Such, however, is 

 not the case, as the following considerations will show. 

 Supposing that, given an adult man who by right of 

 inheritance is an excellent physical being capable of 

 withstanding without difficulty the rigors of present 

 day civilization, we suddenly transfer him to the Arc- 

 tic regions and fail to equip him with proper clothing 

 or housing to withstand the extreme cold. It is quite 

 obvious that under such conditions the man would 

 rapidly succumb to the intense cold, regardless of the 

 genes he had inherited from his forbears. Again, if 

 after a brief exposure to the intense cold and before 

 death, we were to transfer him back to a more suitable 

 environment, we know, from experience, that regard- 

 less of his genes, the individual would show the results 

 of his unfortunate exposure, and would for a time be 

 susceptible to various maladies, particularly respira- 

 tory infections. In other words, while the genes de- 

 termine one's inheritance, environment determines 

 largely the value of this inheritance to the individual 

 concerned. Further, as shown in the simple example 

 cited above, a relatively brief exposure to a distinctly 

 unfavorable environment may so alter one's natural 

 resistance that for a longer or shorter time he is unable 

 to cope with simple variations in an environment to 

 which he is normally relatively resistant. 



There is no reason why these simple concepts should 

 not be applied to the developing fetus in utero. In 

 other words, regardless of the genes which have been 

 passed on to the fetus by its parents, the immediate 

 environment of the fetus must, to a great extent, de- 



