416 FRANKLIN P. MALL 



necessarily fresh, but may possibly vary in age fully a week. 

 In fact he intimates that they are not all fresh, and Triepel makes 

 a slight allowance for this reason. These papers have been care- 

 fully analyzed b}^ Grosser, who finally reached the • conclusion 

 that ovulation does not take place on the 19th, but at the latest 

 on the 16th day after the beginning of menstruation. This 

 figure is not so very far from the average given in my curve; in 

 fact it is a little more than the average age accepted by Triepel 

 as the normal according to the degree of development of the 

 embryo. Triepel has attempted to force a curve which runs 

 exactly 12 days after the average menstrual age of specimens, 

 into one which should be exactly 19 days after this curve, in 

 order to fit Fraenkel's opinion regarding the proper time of ovula- 

 tion. This of course is an impossible feat. 



The conclusion to be drawn, therefore, is that we cannot 

 possibly establish a satisfactory ovulation age of embryos from 

 the data now at our disposal ; but I believe that we have material 

 within our reach whereby we may eventually be able to determine 

 with greater certainty the probable time of ovulation. Before 

 this can be done with the human, however, it will be necessary 

 to study anew the degree of development of the corpus luteum 

 for various days after menstruation, with new material selected 

 from cases which are otherwise normal. This can be done in 

 any large gynecological clinic. 



FERTILIZATION AGE 



According to Bryce and Teacher, the comparative infrequency 

 of pregnancy during continuous cohabitation points to some 

 special circumstance connected with successful impregnation. 

 This circumstance would appear to be simultaneous ovulation 

 and limited power of fertilization on the part of the spermatozoa. 

 As regards the former the work of J. G. Clark is of interest. 

 According to this writer ovulation is accompanied with hypere- 

 mia of the ovary, and, he believes, is hastened by it. He in- 

 jected the blood vessels of an ovary in which there were fresh 

 corpora lutea, as well as swollen Graafian follicles, and found that 



