190 STUDIES ON PATHOLOGIC OVA. 



not, however, without exceptions. Srdinko (1907) 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 which race 

 abortions are less frequent. Further exceptions are reported by Nichols in the 

 case of England and Scotland. According to the last-mentioned author, there is 

 an especially high sex-ratio in legitimate births as compared with illegitimate ones 

 in Rhode Island (104.7 to 98.8), Portugal (107.1 to 100.5), and Greece (114.0 to 

 96.9). He, too, found a greater frequency of still-births and abortions in illegiti- 

 mate pregnancies. Obviously, in such cases there is more concealment and con- 

 sequently still less complete statistics are available than in the case of legitimate 

 pregnancies ending in abortion. 



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

 that of subsequent births, as demonstrated, for instance, in a table by Newcomb 

 (1904). Lewis and Lewis (1906) report that in Scotland the sex-ratio of the .first- 

 born was 105.4, and that of subsequent births 104.8. The secondary sex-ratio is 

 especially high as regards older primiparae, as shown by Ahlfeld (1872, 1876), 

 Janke (1888), and Bidder (1893). That this is also due, in part at least, to different 

 intrauterine mortality may be supported by the citation from Franz that abortions 

 are more than twice as frequent in multipart as in primipara?. Moreover, the 

 first-born children are appreciably smaller than subsequent ones, as demonstrated 

 by Schaetzel (1893) 1 and others, a condition which might suggest a lower rate of 

 mortality during labor. According to Duncan and Duke (1917), however, still- 

 births 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 

 does the percentage of still-births exceed the one of the first-born. However, 

 inasmuch as abortions are much more frequent than still-births, comparatively 

 little importance can be attached to this. The number of children in a family has 

 also been correlated with the sex-ratio; Geissler (1889) found that in families with 

 seven or more children there is a greater proportion of sons than in families with 

 2 to 7 children. Punnett (1903) reached just the opposite conclusion. The former 

 result was confirmed by several other observers (von Korosy, Janke, and Nichols) ; 

 Nichols considers it very probable that in large families the higher proportion of 

 sons is due to a smaller number of abortions, leaving a larger number of children 

 to be born alive, and thus their sex-ratio more closely approaches the primary 

 sex-ratio. 



Besides the above-mentioned causes for the variations found in sex-ratio, 

 many more have been discussed in the literature in an effort to throw light on the 

 question of sex determination. Only a few, if any, of these factors actually exert 

 any influence upon the primary sex-ratio. The changes have all been found in the 

 secondary sex-ratio and the probability is great that the factors causing them 

 affected only the intrauterine death-rate. This is especially true in regard to 



1 Hansen (1913) reports that in Denmark the first born weigh on an average 3,457 grams; the second born 3,607 

 grams; the third born 3,698 grams, the difference between the first and second being much greater than between subsequent 

 ones. The figures for weight at birth, given by Heiberg (1911), show an analogous relation. 



