HEKEDITY AS A FORCE. 19 



the diversity of directions in which it has been 

 employed. 



To invoke the aid of heredity then as an 

 ameliorating agent we must select breeding 

 stock with lines of good ancestors behind them, 

 as well as good individuality in them. In such 

 the especial type desired must be more firmly 

 fixed than in those which have been promiscu- 

 ously bred within the breed or crossed out of it 

 altogether. The inheritance has been intensi- 

 fied in the one, diversified in the other. Taking 

 advantage of this intensification and subjecting 

 its results to proper environment we^may pro- 

 ceed on our upward way. It is the intensified 

 inheritance of the pure-bred which triumphs 

 over the diversified inheritance of the scrub and 

 thus enables us to grade up our stock. Simi- 

 larly it is the diversified inheritance of the 

 grade which precludes his success as a sire, even 

 though he apparently possesses the character- 

 istics of the pure-bred. 



I have conceived, as illustrating the relative 

 values of heredity, the personal equation and 

 environment the simile of a telephone system. 

 The wire strung between two poles may repre- 

 sent heredity. If it is struck by lightning it will 

 conduct the undirected force as it always has 

 conducted it and always will no one knows 

 whither. Environ this same wire with tele- 

 phone apparatus at each end, direct the elec- 

 tricity in its proper volume and proportion and 



