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THE AMEEICAN NATURALIST [Vol. L 



morphologically and we may expect them to differ in their 

 susceptibilities to the alcoholic treatment. One class may 

 he more affected than the other. This might be dne sim- 

 ply to the reason that one class of spermatozoa actually 

 according to mass has more chromatin to be acted upon 

 than the other. And this difference in mass of affected 

 chromatin might be sufficient to give a difference in qual- 

 ity between the individuals arising from the two classes 

 of spermatozoa. 



At any rate, as the accompanying diagram indicates, 

 there is a decided difference between the records of the 

 male and female offspring from treated guinea pigs. The 

 upper half of the accompanying diagram shows that the 

 mortality is higher and the gross deformities more fre- 

 quent among the female offspring sired by alcoholized 

 male guinea pigs than among the male offspring. This 

 difference we may venture to suppose is due to the fact 

 that the female offspring actually receive more modified 

 or injured chromatin from the alcoholic father than do 

 the sons. The diagram is an attempt to represent this 

 larger mass of injured chromatin, the large black X chro- 

 mosome passing to the daughters, while the smaller 

 black Y chromosome is received by the sons. 



Another possible explanation might be that the two 

 heteromorphic sex chromosomes, the X and Y, respond 

 differently to the influence of the alcoholic treatment, the 

 X being the more affected. Such an opinion has some 

 basis, since these chromosomes in the later development 

 of the two sexes seem to carry such a number of contrast- 

 ing qualities according to the splendid evidence presented 

 by Morgan and his associates. One may be permitted to 

 assume on probability, at any rate, that the X and Y 

 chromosomes are qualitatively different in their finer 

 chemical constitutions, and this qualitative difference 

 would necessitate a different response to the chemical 

 treatment on the part of each of the two chromosomes. 



There is also important evidence from the partheno- 

 genetic groups, as, for example, the Phylloxerans and 



