

STUDIES IN THE SEX-RATIO IN MAN. 269 



frequent occurrence in that race. Schultze ('03), on the other 

 hand, has demonstrated that inbreeding has no effect upon sex- 

 determination. The relative infrequency of abortions and still- 

 births among Jews, as has been shown, for instance, by Auerbach 

 for Budapest, explains very simply the fact that the secondary 

 sex-ratio among Jews is higher and therefore closer to the primary. 

 Punnett ('03) and others have shown that the births among 

 classes of lower social status present a lower sex-ratio than those 

 of the rich. The explanation lies again in the fact that the greater 

 frequency of abortions among women of the working classes who 

 can spare themselves less during pregnancy and in whom preg- 

 nancies occur in more rapid succession 1 results in a greater reduc- 

 tion in the sex-ratio, which was originally equal in the two classes. 

 In addition, this greater reduction of the primary sex-ratio in 

 the poorer classes is due to the higher percentage of stillbirths; 

 according to Conrad in Halle among laborers it was 5 per cent., 

 while among upper classes it was only 2.1 per cent. ; and according 

 to Verrijn Stuart ('01) in Holland, among the poor 3.16 per cent, 

 and among the rich 2.50 per cent, of all births. A further ex- 

 ample illustrating how the primary sex-ratio was erroneously 

 thought to be influenced is shown in its difference between legiti- 

 mate and illegitimate children. Heape ('09) states that the 

 sex-ratio of legitimate births among the white population of Cuba 

 is 109.0, stillbirths included; that of the illegitimate only 105.95; 

 there is even a greater difference among negroes, the sex-ratio 

 being 97.91 for illegitimate children and 107.73 f r legitimate 

 ones. Heape immediately draws the conclusion that illegitimate 

 unions result more often in the conception of females than do 

 legitimate unions. According to Diising the sex-ratio of legiti- 

 mate births in Prussia, between the years of 1875 and 1887, was 

 106.37, that of illegitimate only 105.54; the stillborn in legitimate 

 unions amounted to 3.91 per cent.; in illegitimate 5.32 per cent. 

 A corresponding difference was demonstrated by Bertillon ( '96) 

 in the frequency of legitimate and illegitimate abortions. The 

 greater mortality of illegitimate foetuses reduced the sex-ratio 

 to a greater degree. The rule that the sex-ratio is greater in 



1 According to Diising ('84) the longer the intervals between births, the greater 

 is the sex-ratio. 



