STUDIES IN THE SEX-RATIO IN MAN. 263 



only loi.i. Rust ('02) also found the sex-ratio of 454 abortions 

 from the first six months very low, namely 101.8. It is apparent 

 how greatly these figures vary. A new contribution towards 

 the knowledge of sex-ratio of abortions, even if based upon a 

 relatively small amount of material is, therefore, not valueless, 

 especially inasmuch as great care has been taken to determine 

 age and sex. The material for these statistics comprises almost 

 600 fetuses from the collection of the embryological department 

 of the Carnegie Institution. Age classification was based upon 

 the sitting height (Keibel and Mall '10). Rauber published the 

 sex of 57 foetuses with their sitting height; these have been made 

 use of with the author's material. Normal and pathological 

 foetuses, for the most part white, were used in this study. In a 

 limited number of cases no parental history was available; how- 

 ever, it is very probable that the majority of these also were 

 white. Among the few specimens of races other than white, 

 there is a preponderance of negro. The total material from three 

 to ten months comprises 332 males and 315 females, showing a 

 sex- ratio of 105.4. Rauber 's material alone gives a sex-ratio of 

 159. The sex-ratio of the definitely white foetuses amounts to 

 118.7. I* 1 the various months it is as follows: 



Month. Total. White. 



3d 123.7 108.3 



4th 110.5 109.4 



5th 108.1 163.4 



6th 58.8 76.0 



The material upon which are based the sex-ratios from the seventh 

 to the tenth month is too limited to be of much value when repre- 

 sented for each month. The exceptional sex-ratio of the sixth 

 month must be explained as a chance occurrence. The same may 

 be true for the sex-ratio (78.9) of all the pathological foetuses. 

 According to the latter, female abortions are more frequently 

 pathological, a finding which is difficult to correlate with the 

 greater mortality of male foetuses. The greatest deviations in 

 the ratios obtained by Auerbach and Carvallo on the one hand, 

 and by the author on the other, occur in the third and fourth 

 months, for which Auerbach found the ratios to be 322 and 229, 

 and Carvallo, 250. The author's corresponding figures are as 



