242 MENTAL EVOLUTION IN ANIMALS. 



proving that habits intelligently acquired may, like habits 

 acquired without intelligence, be inherited, we have also 

 proved, as in the analogous case of primary instincts, that 

 these habits in the course of generations may vary, that their 

 variations may be inherited, and that the favourable variations 

 may be fixed and further intensified by natural or artificial 

 selection. For it is only by granting all these statements 

 that we can possibly explain many of the foregoing facts. 

 Clearly man could never have produced the artificial instincts 

 of the dog, unless he had practically recognized the facts of 

 variability and inheritance— a recognition which is forcibly 

 expressed in the immense difference between the market 

 value of a pointer or setter of important pedigree, and a 

 pointer or setter whose parentage is unknown. As Thompson 

 well says : — " It would be necessary to recommence the busi- 

 ness of training with each successive generation, if the bodily 

 and mental changes which the animals have undergone in the 

 continued process of domestication had not become so en- 

 grafted as to be propagated with them. These acquired 

 characteristics have gathered fresh strength in each succeed- 

 ing generation, till at length they have assumed a permanent 

 stamp." And if artificial selection is of such high importance 

 in the formation of domestic instincts, much more must 

 natural selection be of importance in the formation of natural 

 instincts. 



