276 THE TREND OF THE RACE 



to one another, the apparent discrepancy being due to the differ- 

 ent degrees of resistance of the bird and the mammalian germ 

 cells to alcohol. Where the direct injury to the germ plasm is not 

 too great the action of alcohol in eliminating the weaker germ 

 cells may outweigh its direct injury to the more vigorous ones. 

 This, if I understand it, is the essential feature of Pearl's attempt 

 to harmonize his own results with those obtained with guinea 

 pigs. Stockard points out that there may have been in Pearl's 

 experiments, not so much an elimination of weaker germ cells, as 

 a very early prenatal mortality, which would naturally be mis- 

 taken for infertility of the eggs. Such early mortality was ac- 

 tually demonstrated in the guinea pigs, especially in the alcoholic 

 strains. But, however this somewhat difficult problem may be 

 solved, — whether elimination occurs before or soon after the germ 

 cells unite, — both Pearl's and Stockard's results may be due to a 

 tendency of alcohol to act injuriously on the germ plasm. The 

 influence of alcohol on the race, however, is very different accord- 

 ing to whether or not the direct injury of alcohol to the germ 

 plasm is outweighed by its operation as a selective agent. 



Confirmatory evidence of the effect of alcohol on the germ 

 cells is afforded by the experiments of Cole and Davis on rabbits 

 by means of double matings. When females were mated at 

 nearly the same time with normal and with alcoholized sires it was 

 found that the sperm of the males that had been given alcohol 

 usually failed to fertilize the ova, owing probably to the influence 

 of alcohol on the vitality of the spermatozoa. 



In regard to the hereditary influence of alcohol m man our 

 evidence is less direct and less conclusive. The great majority of 

 writers on the relation of alcohol to heredity are firmly convinced 

 that the evil effects of alcoholism are transmitted from parents to 

 their children. In recent years, however, expression of opinion on 

 the part of the more scientific students of the subject has become 

 rather more guarded, and by a few writers, prominent among 

 whom is Dr. G. A. Reid, it is held that parental alcoholism has no 

 appreciable influence on the next generation. No critically 

 minded and unbiased person who has become well acquainted 



