94 DEVELOPMENT AND HEREDITY. 



repeated thirty-six times before number four has 

 been attempted ; and as the performance must 

 always begin with number one, it will always have 

 the advantage of number four by thirty-six repeti- 

 tions. 



These characteristics of nervous action which have 

 been mentioned in the few preceding paragraphs, 

 have a very great importance in organic development. 

 The importance, however, must not be measured 

 by the space here devoted to them. Illustrations 

 of the principles might be multiplied without end, 

 and volumes of detailed facts might be collected 

 as proof; but I believe the principles are so gen- 

 erally known and accepted, that it is sufficient merely 

 to recall them to mind. Their importance consists 

 in the fact that they are not pecuHarities of a certain 

 few processes of thought and action, but are uni- 

 versal characteristics of nervous action, so far as 

 we can trace that action ; and accordingly they are 

 dependent upon some fundamental property of living 

 matter. As we believe nervous action to be depend- 

 ent upon the nervous system, so we must believe 

 that the laws of nervous action must be similar 

 according as the different nervous systems are simi- 

 lar. In the gradation of instinct and intelligence 

 which we find as we ascend from the lower animals 

 to the higher, we have a large body of evidence lead- 



