40 Heredity. 



the world around him. The dog, as a living thing, dif- 

 fers from all inorganic bodies, in his power to make this 

 adjustment: so long as he retains this power he lives; his 

 life is a '^continuous adjustment between internal rela 

 tions and external relations." It is plain that this 

 power depends upon experience, but experience depends 

 upon *' memory." So we may state, with truth, that in 

 a certain sense, life is memory; and as the power to re- 

 produce its like is characteristic of all living things, we 

 see that there is in Haeckel's statement a profound 

 truth. 



We know memory, however, only in connection with 

 organization, and if it is true that heredity, the power 

 of an organism to reproduce its like, is simply the 

 memory, by the ovnm, of the experience of its ances- 

 tors, we must believe that there exists in the ovum an 

 organization of some kind to correspond to each of these 

 past experiences. 



We are therefore driven by the hypothesis of peri- 

 genesis back from the hypothesis of cpigenesis to some 

 form of the old evolution hypothesis, for we cannot con- 

 ceive that complicated experiences should exist without 

 complicated structure. 



We are thus compelled to conclude that, while it un- 

 doubtedly expresses a great truth, Ilaeckel's hypothe- 

 sis of perigenesis is not a satisfactory and final explana- 

 tion of the phenomena of reproduction. A satisfactory 

 theory of heredity must explain what it is, in the struc- 

 ture and organization of the ovum, which determines 

 that each ovum should produce its proper organism. 



To state that this organization can be expressed in 

 terms of memory, is simply to state the familiar truth 

 that matter and force are different aspects of the same 

 thing; that all problems of matter may be put into the 



