188 STUDIES ON PATHOLOGIC OVA. 



the uterus more easily than the male." Rauber explains the greater mortality of 

 males by the greater demands of the larger fetuses upon the mother, the latter not 

 always being able to meet them; the production of a female does not require 

 as much from the mother. Lillie (1917) offers the suggestion that the greater 

 mortality among male fetuses is a result of disturbance of the equilibrium that 

 protects the male from the sex hormones of the mother. These are all more or 

 less plausible hypotheses lacking in proofs. As to any real understanding of the 

 unquestionably higher mortality of male fetuses we are still at a loss; attention 

 may be called, however, to the fact that this sexual difference in vitality and power 

 of resistance against disease is not restricted to the period of intrauterine life, but 

 is found also in the first few years of postnatal life, at which time occupation, 

 child-bearing, and other factors can not be held responsible for the difference 

 between the male and female death-rate. 



The excess of male still-births is ascribed by most authors to the more diffi- 

 cult labor attendant upon the greater size of the male, 1 especially the circumference 

 of the head. Button (1910) is of the opinion that at the time of birth the bones 

 of the male skull are, as a rule, more firmly ossified than those of the female. He 

 states also that with the advance of civilization the pelvic development in women 

 is not proportionate to the cephalic development in infants. This perhaps explains 

 the conclusion reached by Bluhm (1912), that the relative number of therapeuti- 

 cally induced premature births is increasing. That labor in case of male children 

 more often demands artificial aid from the obstetrician than in case of females 

 is shown by Prinzing, according to whom 6.18 per cent of male births in Wiirttem- 

 berg called for operative measures, as compared with 4.67 per cent of the female 

 births. This, however, is not due alone to the greater size of the male infant. 

 Von Winckel found that in 566 new-born infants of over 4,000 grams weight 

 operative aid was necessary in only 3 per cent more cases than in births of lighter 

 babies. Furthermore, the more difficult labor of the larger male child can not in 

 itself be held responsible for the high sex-ratio of still-born infants, inasmuch as, 

 according to Treichler (1895), 29.6 per cent, and, according to Prinzing (1907), 

 32.6 per cent, of all still-births are premature, and in the sex ratio of these size 

 plays but little part. According to Ladame (1904), in Switzerland the number 

 dying during labor constituted only 36.4 per cent of the total still-births. Finally, 

 Von Winckel found that the death-rate among 1,000 new-born of over 4,000 grams 

 weight was only 4.17 per cent. 



Sex-ratio has frequently been studied in relation to the pelvic diameters 

 of the mother. The results are somewhat conflicting. Hoffmann (1887), Dohrn 

 (1888), and Orschansky (1894) may be mentioned, according to whom the sex- 

 ratio in children of mothers with narrow pelves is low. In contrast to this, Linden 

 (1884) states it to be 133 in 360 births in which the mothers had narrow pelves. 

 In case the size of the pelvis really has an influence, this can be exerted only upon 

 the secondary sex-ratio in the way of elimination. In the same manner it seems 

 evident that many of the factors which apparently affect the sex-ratio do not 



1 Von Winckel found among 1,000 new-born, of over 4,000 grams weight and 52 cm. length, a sex-ratio of 226. 



