THE ANATOMY OF A 4.2 MM. HUMAN EMBRYO 



95 



(4) to the development of the extremities and disappearance of the tail. The 

 more important of these changes will be dealt with in later chapters. 



FIG. 86. Embryos of the second month from His' Xormentafel (Keibel and Elze). 



Age of Human Embryos. The ages of the human embryos which have 

 been obtained and described can not be determined with certainty, because fer- 

 tilization does not necessarily follow directly after coitus. It has been shown 



