26O ADOLF H. SCHULTZ. 



period it is the result chiefly of tuberculosis, for which disease 

 the common occurrence of anaemic and chlorotic conditions at 

 the time of puberty furnishes an excellent soil. After this age 

 the sex-ratio of mortality increases rapidly and results in the 

 reversion of an excess of males to an excess of females. 



PRIMARY SEX-RATIO. 



The sex-ratio of conceptions cannot be determined directly; 

 however there is an indirect method of solving the problem of 

 the original sex-ratio by means of computing the mortality of 

 embryos and foetuses. Only in case the sex-ratio of those dying 

 in utero is equal to the secondary sex-ratio, will the primary be 

 equal to the secondary. If male abortions were absolutely the 

 same as female, then the primary sex-ratio would be smaller 

 than the secondary. If the sex-ratio of mortality during preg- 

 nancy exceeds the sex-ratio of the livingborn, then the sex-ratio 

 of conceptions will of necessity be greater than the secondary and 

 indeed all the more so as the total mortality becomes relatively 

 greater. It is necessary, therefore, to consider two factors in 

 order to deduce the primary from the secondary sex-ratio. The 

 following schematic representation will illustrate this : 



1. How many male abortions and stillbirths occur to every 

 IOO female abortions and stillbirths? 



2. How many abortions both male and female, occur to every 

 100 living born? 



100 living born with sex-ratio 105.5 + a stillbirths and abor- 

 tions with sex-ratio b. 



100 -f- a conceptions with sex-ratio x. 



This scheme becomes complicated by differences in sex-ratio 

 of mortality and in the relative rate of mortality in the various 

 periods of pregnancy. The relative number of stillbirths differs 

 to some extent according to the various authors. This is in part 

 explained by the fact that the statistics are taken from various 

 countries. Rauber states that the stillbirths amount to 4 per 

 cent, of the annual 1,800,000 births in Germany. According to 

 Carlberg ('86), the proportion of stillbirths to the total number 

 of births in Livland lies between 2.58 and 2.90 per cent., while 

 the percentage for Western Europe lies between 4 and 4.5 per 



