AGE OF HUMAN EMBRYOS 



419 



menstruation untenable, and the possibility of a relation between 

 orgastic reaction and ovulation is not to be overlooked. 



An interesting study in this connection has been made by 

 Siegel," using the wives of German soldiers as his subjects. 

 These women, who became pregnant during their husband's 

 furlough, came to the maternity hospital to be confined, and 



DAYS 

 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 lb 17 18 19 20 21 22 23 24 25 26 27 28 



Fig. 2 Cohabitation curve according to Siegel. The main division of the 

 menstrual month and the probable time of ovulation are given. One hundred 

 cases of pregnancy, occurring in the wives of soldiers after their husbands' fur- 

 lough of one week. Each day of the furlough is entered as a possible day of con- 

 ception. In all probability the 1st to the 4th day and the 18th to the 21st day 

 belong to the sterile portion of the month. 



it was easy to obtain records of the menstrual history as well as 

 the times of furlough, which in each case was of about a week's 

 duration. Figure 2, taken from Siegel's paper, gives the result 

 of the tabulation of 100 of such cases. Each day of the furlough 

 is entered in the curve. Thus, if the furlough lasted from the 



17 Siegel, P. W. 

 Woch., 41. 



1915 Warum ist der Beischlaf befruchtend? Deut. Med. 



