V AGE OF HUMAN EMBRYOS 



411 



Bryce and Teacher, that there is this interval of two days between 

 copulation and fertihzation. For the sake of completion the 

 curve giving the His convention is also included in the figure. 

 I wish again to emphasize the fact that the curves given in the 

 figure are not constructed from the records of the specimens in 

 question, and it is quite clear, I think, that the new cases give no 

 reason for materially altering the mean copulation curve as given 

 by me in the Manual seven years ago. The relation of these 

 curves to the ovulation age and to the fertilization age remains 

 to be established, and as far as the evidence will permit this will 

 be done in the following paragraphs. 



OVULATION AGE 



The question of the time of ovulation in relation, to menstrua- 

 tion or to copulation is by no means answered, although the 

 literature upon the subject is extensive. If the time of ovulation 

 could be definitely determined we would then be able to ascertain 

 the ages of embryos with very fair precision. Wherever possible 

 we have collected ovaries with our specimens, but so far have 

 obtained only one accompanying a young ovum. This speci- 

 men, No. 97'0 in our collection, is from a Filipino girl, 16 years 

 old, who died four days after taking hydrochloric acid with sui- 

 cidal intent on account of her condition. The ovum, which 

 measures 5x3 mm., is not quite normal in appearance but is well 

 implanted. The corpus luteum is well formed, and solid, with 

 no remnant of blood within it. The Herzog^ specimen, which 



7 Herzog. 1909 A contribution to our knowledge of the earliest known stages 

 of placentation and em^)ryonic development in man. Am. Jour. Anat., vol. 9. 



