188 



HABIT AND INTELLIGENCE. 



[chap. 



Benefit 

 of slight 

 mixtures 

 of race. 



Mixtuies 

 of unlike 

 races. 



Slight 

 changes are 

 agreeable, 

 great ones 

 disagree- 

 able. 



Summary. 



seed from a distance, instead of sowing that which has 

 been raised in the same farm or garden. 



I agree with Darwin ^ in believing that there is a pro- 

 found connexion between this last-mentioned law and the 

 general law, that slight mixtures of race, or " crossings of 

 the breed," tends to promote the health and vigour of the 

 race. I say slight mixtures, because very different races 

 will not mix at all : the pollen of a rose on the stigma of a 

 foxglove, for instance, would produce no more effect than 

 if it were so much dust blown off the road. And between 

 these two extremes of kindred races which are benefited 

 by mixture, and totally distinct races which will not mix 

 at all, there is a wide class of intermediate cases. Some- 

 times, when two distinct species of plants are hybridised, 

 seed is produced, but in less abundance than if the plant 

 bearing it had been fertilized with pollen of its own species. 

 Sometimes, among animals, the oftppring is vigorous, but 

 infertile, and cannot give origin to a hybrid race : the 

 mule, between the horse and the ass, is a well-known 

 instance of this. Sometimes offspring is produced, but is 

 weak, and dies early ; sometimes, in the case of birds, 

 without being able to break through the egg.^ 



There is another set of facts which I will mention here, 

 though they are not relevant to the subject of the present 

 chapter, because I believe they stand in the closest con- 

 nexion with the laws of habit and of the effects of changing 

 circumstances. I mean that, among conscious organisms, 

 slight changes are agreeable, but great changes painful, or 

 at least disagreeable. This law is a most important one in 

 mental science. 



I have now enumerated four pairs of laws w^hich, it is 

 scarcely possible to doubt, stand in the closest relation to 

 each other. They are as follow : — 



1 Origin of Species, p. 318. 



^ Ibid. p. 315. See the whole chapter on Hybridism. Darwin says, 

 that the impossibility of obtaining hybrid offspring at all in some cases, 

 and the infertility of such offspring in other cases, are very distinct facts : 

 but I think it needs no proof that they are facts of the same class. In 

 the former, we cannot obtain hybrid individuals : in the latter, we cannot 

 obtain a hybrid race. 



