66 The Morality of Nature 



have been chosen by the spider. But in fact the web 

 carried by the wind could not be directed by choice. The 

 first Hne perhaps failed, and another was tried, and fell 

 inappropriately, and still another; and at last one caught 

 upon a place which was an opportunity worth seizing. Thus 

 we see three or four efforts for chances tried and only one 

 successful. And so it may properly be in nature's variations 

 of structure. Many may be futile. Yet just as the spider's 

 efforts were all based upon its experienced habit, so may 

 the variations of natural forms be based upon previous 

 things promising probable success, although never certain. 



Thus we see that environment offers many promptings, 

 more or less favorable, or more or less hostile and difficult. 

 These impulses stimulate effort, and the creature responds 

 to them, and some of these responses succeed and if often 

 repeated, are permanently adopted. Some of these new 

 forms and new habits become hereditary or are hereditable 

 at once. Therefore, it is evident that the environment of 

 one period affects the previous heredity, and these two 

 factors together, that is old heredity as the main force and 

 new environment as a minor force make the heredity of the 

 next period. So when we discuss heredity and environment, 

 they must not be treated as unrelated forces, but as two 

 parts or stages of natural influence under a common law. 

 A creature at birth, without experience, is a product of 

 heredity chiefly. Environment has done little to him. 

 Heredity still continues after that to affect him in great 

 degree, but from the time his own life begins it is also 

 affected by environment. If this latter is different from 

 that of his ancestors it is likely to change him, or to develop 



