2 JO ADOLF H. SCHULTZ. 



legitimate than in illegitimate births is not, however, without 

 exception. Srdinko ('07) found that the sex-ratio of legitimate 

 births in Austria was lower than that of the illegitimate, and 

 explains this by the fact that the illegitimate are for the most 

 part Jewish, in w r hich race abortions are less frequent. According 

 to a number of authors, the sex-ratio of first born is greater than 

 that of subsequent births. 1 It is especially high in older primi- 

 parae, as shown by Ahlfeld ('72 and '76), Janke ('88) and Bidder 

 ('93). Lewis ('06) reports that in Scotland the sex-ratio of first 

 born was 105.4 an d that of subsequent births 104.8. That this 

 at least in part is also due to different intrauterine mortality may 

 be supported by the following citations. According to Franz, 

 abortions are more than twice as frequent in multiparse than in 

 primiparse. Moreover, the first-born children are appreciably 

 smaller than subsequent ones, as demonstrated by Schaetzel 

 ('93), a condition which w T ould suggest a lower rate of mortality 

 before birth as a result of the relatively fewer demands made 

 upon the mother (Rauber). Hansen ('13) states that in Den- 

 mark the first-born weigh on an average 3, 457 grams; the second- 

 born 3,607 grams, third-born 3,698 grams, the difference between 

 the first and second being much greater than between the sub- 

 sequent ones. Stillbirths, however, according to Duncan and 

 Duke ('17) are more frequent among first-born than among second- 

 and third-born, in spite of their smaller size; only in the case of 

 children from the sixth pregnancy dies the percentage of still 

 born exceed that of first-born. However, inasmuch as many more 

 abortions than stillbirths occur, comparatively little importance 

 can be attached to this. 



Besides the above mentioned causes for the variations found 

 in sex-ratio, many others have been discussed in the literature. 

 Only a few of these factors actually exert any influence upon the 

 sex-ratio of conceptions. The changes have all been found in 

 the secondary sex-ratio and the probability is great that the fac- 

 tors causing them play not a sex-determining but a sex-elimi- 

 nating role. This is true chiefly in regard to changes resulting 

 from locality, such as rural and urban districts, from age, nutri- 



1 A table demonstrating this may be consulted in Newcomb's article. 



