150 CHARLES R. STOCKARD AND GEORGE N. PAPANICOLAOU 



stronger to be born. In addition to this, it must also be recog- 

 nized that the ability of the female to properly nourish the mem- 

 bers of the large litters is somewhat overtaxed. Three or less 

 than three embryos are very well nourished by normal mothers. 

 It must be recognized here that the inferior records of the alco- 

 holic lines are not alone produced by alcoholic mothers, but 

 come also from alcoholic fathers as following tables will show. 



The survival records of the normal inbred lines are about the 

 same as those from the straight control, and are almost equally 

 superior to the alcoholic lines. 



The alcoholic inbred animals have a survival record closely 

 similar to the straight alcoholic lines, and again decidedly inferior 

 to either the normal or normal inbred lines. 



The fifth horizontal space contains the mortality records 

 which are the reverse of the survival records just considered. 

 However, we have given here not only the actual mortality in 

 litters of different sizes, but have corrected the total mortality 

 record on the basis of the occurrence of large and small litters 

 and their mortality in the different lines as compared with the 

 control. We have also expressed the mortality in numerical 

 proportion in the several lines, taking the control as 100. The 

 total mortality in the normal lines is 22.31 per cent. This is a 

 very good record, since it not only includes the postnatal mor- 

 tality, but all exact prenatal mortality as well. We mean by 

 exact prenatal mortality those cases of absorption in utero and 

 premature abortion which were actually observed, and not those 

 calculated on the basis of size of litter, mating failures, etc., as 

 was discussed in connection with the productivity of the different 

 lines., 



The total mortality of the normal inbred is 21.95 per cent, or 

 ahnost the same actually as well as when corrected for litter 

 sizes as the straight normal lines. 



The total mortality of the alcoholic lines without inbreeding 

 was 35.52 per cent, or almost 1.6 times greater than the mor- 

 tality of the control. But this does not fully represent the real 

 difference between the two lines unless it be corrected on the 

 basis of the mortality record for the different-size litters in the 

 alcoholic and the normal. The mortality is much higher among 



