MODIFICATION OF THE GERM-CELLS IN MAMMALS 171 



There is a high percentage of small litters and a low percentage of 

 large litters, thus giving next to the lowest average litter con- 

 tained in all the records, only 2.30 against 2,77 for the normal. 

 The average litter weight is very low on account of the small 

 average litter size. When this is corrected for the proportion of 

 weight to number of individuals in the control litters these 

 small litters from the treated fathers weigh more for their size 

 than do the control, being over 6 grams heavier. This is not 

 an actual advantage since the majority of j^oung born in small 

 litters of one and two are larger than those born in high litters 

 of four or five. The percentage of mating failures is unusually 

 high, 23.52 per cent against only 4.54 per cent in the control. 

 All of these facts would seem to indicate that the treatment of 

 the fathers had evidently lowered their productivity or fertility, 

 causing them to fail to sire offspring in almost one-quarter of 

 the matings and to beget unusually small litters in the other 

 three-quarters of the cases. There must have also been a high 

 'early prenatal mortality' in view of the remarkably great per- 

 centage of small litters and high percentage of mating failures. 

 We must necessarily divide the mortality into prenatal and 

 postnatal, and the prenatal again into 'early prenatal,' as in- 

 dicated by the small average size litter and high number of 

 mating failures, and 'late prenatal' based on the exact observa- 

 tions of absorptions, abortions, and still births. 



Two-thirds of the offspring from treated fathers survived 

 against over three-fourths from the control. The prenatal mor- 

 tality is a larger proportion of the total than in the normal. The 

 total mortality when corrected to the normal rate for the differ- 

 ent-size litters in which the animals were born is 178 in terms of 

 the control as 100. This is only slightly below the mortality 

 rate of 189 for the entire non-inbred alcoholic group. 



When the mother alone was treated the records of the off- 

 spring differ considerably from the above. The percentage of 

 small litters is only slightly higher than the percentage of large 

 litters, and the average-size litter, 2.78, is as large as the nor- 

 mal. There are very few mating failures, in this regard again 



