90 THE DATA OF BIOLOGY. 



bination. Nevertheless, answering though it does to so 

 many requirements, this definition is essentially defective. 

 The definite combination of heterogeneous changes, both 

 simultaneous and successive, is a formula which fails to call 

 up an adequate conception. And it fails from omitting the 

 most distinctive peculiarity the peculiarity of which we 

 have the most familiar experience, and with which our notion 

 of Life is, more than with any other, associated. It remains 

 now to supplement the conception by the addition of this 

 peculiarity. 



