208 CROSSING AND CLOSE-INTERBREEDING. 



degree of good, and a like degree of evil, when 

 there is a like degree of relationship, or of distinction 

 in individuals of the same species. . Why do the evil 

 effects of close-interbreeding, recur, at different periods, 

 with different individuals of the same species ? Why 

 is close interbreeding of such doubtful, and varying 

 effect? Why is it .so problematical, in any given 

 degree of interbreeding, whether evil, or good, will 

 result? Why is it, that good frequently results, from 

 this process, when by " a general law of nature," as 

 Darwin has it, evil is essentially inherent in such a 

 process ? He himself says, again and again, that close- 

 interbreeding is that process, upon which breeders 

 mainly rely, to effect improvement in their breeds. 

 He also shows, that different species of animals and 

 plants, are differently affected, by the same degree of 

 interbreeding; and that different animals and different 

 plants, of the very same species, are also differently 

 affected. The effects of the same degree of inter- 

 breeding, are also shown to be different, in different 

 varieties; different, in individuals of the same variety; 

 different, in individuals of the same herd or flock; 

 different, in individuals of the same family; aye, differ- 

 ent in flowers on the same plant; different, in flowers 

 on the same bough or branch; and different, in flowers 

 on the same twig! 



The good, from the same degree of crossing, like- 

 wise, differs, in the same way. Why this inconstancy? 

 Why this variability, in the effects which follow, if 

 there be " a great law of nature ? " 



Why is it, if the evil effects are due to interbreeding, 



