506 POPULAR SCIENCE MONTHLY 



is fallacious. The way fertility is calculated is to divide the number 

 of births in a given year by the number of marriages contracted during 

 the same year. Only very few of the births during any one year are 

 due to the marriages during that year, but are from couples married 

 within the preceding twenty-five years. If the number of mixed mar- 

 riages did not increase, such a division would more or less accurately 

 give us the average fecundity. But as has been shown above, the num- 

 ber of mixed marriages increases regularly in every country considered, 

 so that the births of the year considered represent the fecundity of a 

 smaller number of marriages than have been contracted during this 

 year. A smaller fertility is thus apparently seen among the mixed 

 marriages. I will illustrate this by figures obtained by Euppin about 

 conditions in Prussia : During 1901 there were 4.2 births to each 

 christian marriage; 2.80 to each Jewish marriage; and only 1.80 to 

 each marriage of a christian to a Jewess and 1.53 to each marriage of 

 a Jew with a christian woman. But recalling that only a few of these 

 births were the results of marriages contracted during 1901, but repre- 

 sent marriages for about twenty-five years, we are led to investigate 

 further. In 1876 only 256 mixed marriages were contracted in Prussia, 

 and during the twenty-five succeeding years they increased annually, 

 reaching 455 in 1901. If we accordingly calculate the birth rate for 

 1901 on the basis of the average number of marriages during these 

 twenty-five years (1876-1901), the result is entirely different. Ruppin 

 shows that the rates calculated by this method are 5.07 births to each 

 christian marriage, 2.96 to each Jewish marriage, 2.5 to each marriage 

 of a christian with a Jewess and 2.35 to each marriage of a Jew with 

 a christian woman. The difference is thus not much in favor of pure 

 Jewish marriages when compared with mixed. But even this does not 

 give us a clear picture, because in many mixed marriages one of the 

 parties accepts the religion of the other, and the births are then recorded 

 not as the issue of a mixed marriage, but of a pure christian or pure 

 Jewish marriage, as the case may be. Many births resulting from 

 mixed marriages are consequently missing from the official records, 

 thus reducing the average number of births perceptibly. Considering 

 this and, in addition, the fact that most of the mixed marriages occur 

 in large cities, where the birth rates are much lower than in the coun- 

 try, one is bound to agree with Ruppin that the Prussian official statis- 

 tics do not support the theory that mixed marriages are less fertile 

 than pure manages. 



There is very little to be said about the alleged physical deteriora- 

 tion of the offspring of mixed marriages, because it has not been proved 



