128 CATTLE-BREEDING. 



treatise on this subject which I have met with, 

 concurs." And again he says, in summing up 

 his observations on this subject: " Finally, when 

 we consider the various facts now given which 

 plainly show that good follows from crossing 

 [the word is here used with reference to cross- 

 ing families and also 'distinct varieties'], and 

 less plainly that evil follows from close inter- 

 breeding, and when we bear in mind that 

 throughout the whole organic world elaborate 

 provision has been made for the occasional 

 union of distinct individuals, the existence of a 

 great law of Nature is, if not proved, at least 

 rendered in the highest degree- probable 

 namely, that the crossing of animals and plants 

 which are not closely related to each other is 

 highly beneficial, or even necessary, and that 

 interbreeding prolonged during many genera- 

 tions is highly injurious." 



In the course of a lengthy and able exami- 

 nation of this subject, and the facts illustrative 

 of it, Mr. Darwin shows the tremendous influ- 

 ence of a cross in such directions as increased 

 fruitfulness upon deeply inbred stock. In our 

 present inquiry we are considering the case of 

 a constant adherence to a system of outcrosses 

 of crosses chosen for merit simply and for 

 the negative quality of non-relation conse- 

 quently the sudden and deep impression he 

 alludes to is scarcely to be expected. The 



