RELATION OF RACE CROSSING TO THE SEX RATIO. 



197 



2. If such a tendency appears to exist is it {a) uniformly shown 

 in all the matings considered, and {/>) numerically great enough 

 in amount to be considered significant when tested by probable 

 errors ? 



Data. 



The raw material on which this paper is based is set forth in 

 Table I. The figures are extracted from Volumes VI. to XV. 

 inclusive of the AiDiuairc statistiqtie de la ville de Biienos-Ayres} 



Table I. 

 Sex Distribution of Legitimate Births. Raw Data. 



It is at once apparent that these statistics show essentially the 

 same relation of the sexes as that usually found when large num- 

 bers of human births are examined, namely, a preponderance of 

 males. The extent of this preponderance may be shown best by 

 putting the data in the form of sex-ratios. In this paper the sex 

 ratio will be taken as the number of males to each 100 females. 

 The sex ratios deduced from the totals of Table I. and their 

 probable errors are given in Table II. It does not appear to be 

 necessary or advisable to deal with the single years separately. 

 The method of determining the probable errors of the sex-ratios 

 was to determine first for each mating the probable error of the 

 absolute frequency of males, considering this as a simple class 



' Published by the Direction generale de la statistique municipale, Buenos Ayres. 



