46 Heredity. 



(Encyc. Brit., Art. Evolution), '' Harvey's definition of 

 a germ as * matter potentially alive, and having within 

 itself the tendency to assume a definite living form,' 

 appears to meet all the requirements of modern science. 

 For notwithstanding it might be justly questioned 

 whether a germ is not merely jootentially but rather 

 actually alive, though its vital manifestations are re- 

 duced to a minimum, the term potential may fairly be 

 used in a sense broad enough to escape the objection. 

 And the qualification of potential has the advantage of 

 reminding us that the great characteristic of the germ is 

 not so much what it is, but what it may under suitable 

 conditions become. *^From this jioint of view the pro- 

 cess, wdiich in its superficial aspects is epigenesis, ap- 

 pears in essence to be evolution, . . . and development 

 is merely the expansion of a potential organism or 

 organic preformation according to fixed laws." 



