MODIFICATION OF THE GEEM-CELLS IN MAMMALS 167 



the control animals in a number of important qualities that ren- 

 der them less capable of survival. 



These two factors, the constant introduction of more normal 

 germ plasm and the elimination of all the weaker alcoholic indi- 

 viduals so that only the stronger reproduce, may finally in late 

 generations so purify the alcoholic lines as to cause them to 

 attain a condition equally as good as the normal. 



The sixth and last column of table 2 may illustrate such a 

 condition, though it contains the records from only a few ani- 

 mals. These animals are descended from one or more treated 

 great-great-grandparents, the F4 generation. They are four 

 generations removed from the alcoholic treatment. 



The average-size litter is almost as large as in the control, 

 and on the basis of its size it is actually heavier than the control 

 average. It may be said from the evidence shown that the pro- 

 ductivity here is equally as high as in the control. 



A higher percentage of individuals survived than among the 

 control, and even though the mortality figures are small there was 

 certainly no tendency toward a high prenatal mortality. On the 

 contrary, there was scarcely any prenatal mortality, so that the 

 record in no way resembles that of the alcoholic lines. On the 

 basis of 1)00 for normal stock mortality, the mortality here cor- 

 rected for litter size is only 84, or 16 per cent better than the 

 normal. It is actually in the table 5 per cent lower than the 

 control. 



After having considered the last column, the F4 animals with 

 their very good record, it should be recognized that these same 

 animals are included with the F2 and F3 individuals in the 

 fourth and fifth columns. Their presence in these columns, 

 particularly in the fifth, has tended to incline the records toward 

 the normal. One must realize, therefore, that the Fo and F3 

 animals if considered alone would present even stronger alcoholic 

 records than are indicated in the fourth and fifth columns. 



The table shows that the nearer to the direct alcohol treatment 

 an animal is produced, the more inferior in quality it will be as a 

 result of the high amount of modified germ plasm contained in the 

 germ-cell complex from which it arises. Therefore, the records 



