No. 448.] HEREDITY AND ENVIROXM EXT. 



same influences, so we find the plants or aniir 

 behaving and being in the main alike at the - 

 they are unlike the plants and animals of all other k 

 they are subjected to the same infiuences. In tb 

 composition and adjustment to these forces we h; 

 reason for the diversity of behavior of different a- 

 and lifeless things. They are all inHueiiced by 

 what they are represents their reactions to tliese 

 forces. The fundamental likeness of parent ; 

 represents the continuity of substance and of 

 superficial differences represent the different intlue 

 they have been subjected and to which tlie)- ha\e 

 all common salt crystals are of exactly the same 

 the puppies of a litter are exactly alike. Hut tlv 

 are fundamentally alike, and so are the j)uppies. 

 vastly greater complexity — considered mei-ely c 

 the moment — one should exjK'ct puppies to var\- v ■ 

 crystals. But neither salt crystals nor pupi)ies 

 not to be salt crystals or puppies ; the continue 

 conserve their fundamental characters. 



In this discussion two things have been assume 

 tinuity of substance from parent to offspring, and th 

 the power of reaction, of this substance to the \ ari: 

 its environment. These two facts are essential 

 My contention is merely that in the continuous 

 factors of the environment we have forces, in Hue 

 under the operation of which the living substan -' 



Continuously and unchangingly reacts. These ir 

 factors in the environment, but at the same time, li 

 they are factors in heredity. The clearer our co 

 the fuller our knowledge of the irritability and 

 reaction of living organisms to external stimuli, th - ^ 

 mass of unexplained though not unexf^kunable plv 



