6 WILD TRAITS IN TAME ANIMALS. 



failure has resulted because the knowledge of 

 evolutionary laws has been merely theoretical 

 and superficial. There has been an immense 

 amount of literature upon the subject of Darwin- 

 ism poured out during the last thirty years, much 

 of it of a very speculative and evanescent char- 

 acter. One can hardly wonder, therefore, if 

 many students are somewhat bewildered as a 

 result of trying to inform themselves from such 

 sources. If the amateur naturalist is to profit 

 by the new doctrine his information must be 

 thorough and based upon experience, even al- 

 though it may not be extensive. When we are 

 going to make use of knowledge for some prac- 

 tical purpose, we generally find that it is necessary 

 to have a much more thorough grip of our subject 

 than can be gained from studying verbal state- 

 ments and formulae. It is often absolutely impos- 

 sible to obtain from books the kind of knowledge 

 which is demanded in practice. What traveller 

 about to undertake an expedition in which a 

 knowledge of horsemanship or cycling was neces- 

 sary, could expect to reach his goal if he contented 

 himself with reading exhaustive treatises on these 

 arts ? The very act of walking, which we deem 

 so simple, would, if taught in an abstract and aca- 



