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THE AMERICAN NATURALIST [Vol. L 



male are more injured than the male offspring of treated 

 fathers. The next horizontal line shows that the off- 

 spring from treated mothers are far better than from 

 treated fathers, having a much lower mortality. The 

 male germ cell is more affected by the alcohol than the 

 ovum, therefore treated fathers produce poorer offspring 

 than treated mothers. 



The heterogeneous female descendants from an alco- 

 holized paternal grandfather are more affected than the 

 male, 39.47 per cent, mortality to 27.77 per cent. 



The male and female descendants from an alcoholized 

 paternal grandmother show about equal conditions, 32.43 

 per cent, male mortality to 30.3 per cent, female mortality. 



The heterogeneous female descendants are inferior to 

 similar male descendants from an alcoholized maternal 

 grandfather, 40.72 per cent, female mortality to 32.25 per 

 cent, male mortality. 



The male and female descendants are about equally 

 strong from an alcoholized maternal grandmother, 21.74 

 per cent, male mortality to 22.22 per cent, female mor- 

 tality. 



Although explanations of the above differences between 

 the ways in which the male and female guinea pigs are 

 affected by the treatment, as well as explanations of the 

 different records of the grandsons and granddaughters 

 from alcoholization of different ones of the four grand- 

 parents, are difficult to give at the present stage of the 

 experiment, a tentative explanation based on the compo- 

 sition of the chromosomal complex is certainly suggested. 



General Considerations 

 In the case of the male guinea pig, according to the 

 studies of Miss Stevens ('11), two kinds of spermatozoa 

 are produced. The one has a large X chromosome, the 

 female-producing spermatozoon, and the other contains 

 a corresponding small Y chromosome, which from homol- 

 ogy with other forms we may consider to be the male- 

 producing. The two classes of spermatids are different 



