1 62 DOMESTICATED ANIMALS AND PLANTS 



selected for high oil produced in the ninth year a crop as high 

 as 7.29 per cent oil and one as low as 2.58 per cent. Note, 

 also, the rapid rate at which the distributions separate from 

 each other, — so rapid, indeed, that in the fourth crop (1900) they 

 no longer overlap but entirely part company ; that is, the lowest 

 of the high oil is higher than the highest of the low oil.^ 



If the offspring of the exceptional parent is in many cases so 

 decidedly exceptional, how did the tradition start about the 

 mediocre sons of great men ? Naturally enough. Some of these 

 sons are truly mediocre, even inferior, as we have seen, and in 

 this, as in other matters, a few cases make a great impression, 

 provided they are sufficiently striking. Every preacher's son that 

 goes wrong attracts special attention, — even more attention than 

 does the long line of divines like the Edwardses or the Adamses, 

 in which greatness almost invariably descended from father to 

 son for many generations. This impression is akin to that 

 other popular fallacy that people choose opposites in matrimony ; 

 that is, that tall people prefer short mates ; dark-haired prefer 

 light ; phlegmatic prefer vivacious, etc. Now the facts are, so 

 far as they have been studied, that people prefer and choose 

 their like to a surprisingly large degree. For example, the 

 correlation or ratio of correspondence between husbands and 

 wives amounts to 0.28 in stature and about the same in eye 

 and hair color, whereas if they tended to choose opposites, 

 it would be negative, and if they were indifferent, it would be 

 zero. The fact is, that if we see one tall woman with a little 

 husband, or the reverse, the grotesqueness of it all strikes our 

 attention and we remark about it, reminding ourselves again of 

 the "law of dissimilars" ; whereas we fail to notice the large 

 number of properly assorted people that pass and repass, and 

 thus overlook the real law that men and women in general mate 

 by similarities and get along best when they do so. These few 

 illustrations will show the need of accurate and somewhat exten- 

 sive observation before hastening to generalization. 



1 For a fuller discussion, see " Principles of Breeding," pp. 492-499. 



