i8 4 PHYSIC 



layers. This modification, we have observed, is a life-long 

 one, stretching from the earliest development of the 

 embryonic "limiting membrane" and foetal skin to the 

 most wrinkled old age, and determined by the circum- 

 stances of environment and the altering conditions of life 

 and work. Thus the respective proportions in regard 

 to fulness of development and complexity of textural 

 arrangement of the nervine and blood circulatory media 

 change "with the changing years." 



