56 MAMMARY APPARATUS OF THE MAMMALIA 



possibility of filling up these gaps to the 

 kindness of Professor Hill, and if I have 

 succeeded in completing my work, the results 

 will be in great measure due to him. 



When I came to London to study Professor 

 Hill's preparations in University College, I had 



Fig. 19a. — Six-Days-Olb Embryo of "Didelphys 

 MAKSupiALis." (After Hill.) 



iTia, Primary-primordium. 



definite hopes of being able to discover the 

 first primordia of the mammar}' apparatus. But 

 I had not expected that this discovery would 

 be so simple as it turned out to be. 



My first successful observation was made 

 upon an embryo of Didelphys marsupialis, 



