410 



FRANKLIN P. MALL 



according to their degree of development as given by Triepel in 

 order to show that he has practically adopted the curve of de- 

 velopment given by Bryce and Teacher and also by myself. 

 He has really taken what I have designated as the copulation 

 age, minus about two days for each stage, assuming, as do also 



7p 80 90 |I00 I DAYS 



2 3 4 5 6 7 e 9 10 II 12 13 14 15 WEEKS 



Fig. 1 Menstruation age and copulation age taken from the curve constructed 

 by me and published in the Manual of Human Embryology. All embryos are 

 entered with CR length. I have also added for the sake of comparison the curve 

 giving the convention of His. NL and CR give the neck-rump and crown-rump 

 lengths respectively, according to His. The fertilization age is according to 

 Bryce and Teacher for smaller embryos, and according to Triepel for larger ones. 

 The dots record the menstrual age of the embryos under consideration, and the 

 squares the copulation age. The crossed squares mark the best records, as men- 

 tioned in the text. 



It may be noted again that the curves are not constructed from these records, 

 but the records are entered to test the curve. 



