CERTAIN UNDETERMINED EACTORS IN 

 HEREDITY AND ENVIRONMENT. 



GEORGE J. PEIRCE. 



In a paper read before the Botanical Section at the Pittsburg 

 meeting of the American Association for the Advancement of 

 Science ^ I suggested that certain factors of the environment 

 were constantly ignored in such discussions of heredity as I had 

 seen or heard. This paper constitutes substantially the last 

 section of my book.'^ Since certain letters which I have 

 recently received, make me feel that in this section I have 

 expressed myself so concisely that my full meaning is not alto- 

 gether clear, I take this opportunity to give somewhat ampler 

 treatment to the subject. 



The word environment is used ignorantly by everyone, for no 

 one has ever succeeded in making a complete analysis of what 

 is meant by this collective term. Furthermore, although we 

 speak of an organism as reacting to its environment, it does not 

 react to its environment as a whole but to each of one of the 

 separate influences which are the factors of its environment. It 

 is, therefore, very important to know what these factors are, and 

 what are their effects. We know that if two of these influences 

 are opposite and equal, there will be no visible reaction, although 

 the organism will be affected by both. There may be internal 

 results of these influences, results which, however, may not be 

 perceptible. If one of these opposite influences be lessened or 

 eliminated, the effect of the other becomes perceptible. We 

 judge, then, the influence of the various factors which we are 

 now able to distinguish from one another as constituting the 

 environment, only by their perceptible effects. It is conceivable 

 that some effects are so long deferred that they are coincident 

 or at least contemporaneous with the effects of other and more 

 recent stimuli. For this reason these long deferred effects may 



1 Abstract in Scietice, XVI. p. 137, 1902. 



' Peirce, G. J. Text hook of Plant Physioloi^y. 279-83' New York, 1903. 

 285 



