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POPULAR SCIENCE MONTHLY. 



of the V class — which is the highest in the table. Of its 34 or 35 

 j-ons, 6 come from V parentages, 10 from U, 10 from T, 5 from 

 S, 3 from E, and none from any class below E. But the numbers of 

 the contributing parentages have also to be taken into account. When 

 this is done, we see that the lower classes make their scores owing to 

 their quantity and not to their quality; for while 35 V-class parents 

 suffice to produce 6 sons of the V class, it takes 2,500 E-class fathers 

 to produce 3 of them. Consequently the richness in produce of V-class 

 parentages is to that of the E-class in an inverse ratio, or as 143 to 1. 

 Similarly, the richness in produce of V-class children from parentages 

 of the classes U, T, S, respectively, is as 3, lli/^ and 55, to 1, More- 

 over, nearly one-half of the produce of V-class parentages are V or U 

 taken together, and nearly three quarters of them are either V, U or 

 T. If then we desire to increase the output of V-class offspring, by far 

 the most profitable parents to work upon would be those of the V class, 

 and in a threefold less degree those of the U class. 



When both parents are of the V class the quality of parentages is 

 greatly superior to those in which only one parent is a V. In that 

 case the regression of the genetic center goes twice as far back towards 

 mediocrity, and the spread of the distribution among filials becomes 

 nine tenths of that among the parents, instead of being only three- 

 quarters. The effect is shown in Table II. 



Table II. — Distribution of Sons. (I) One parent of class V., the other un- 

 known. (2) Both parents of class V (from Taile II., with decimal point 

 and an o). 



Position of the filial center of (1)=1.44, of (2) =2.89. When both par- 

 ents are T it = 1.58. 



There is a difference of fully two divisions in the position of the 

 genetic center, that of the single V parentage being only a trifle nearer 

 mediocrity than that of the double T. Hence it would be bad economy 

 to spend much effort in furthering marriages with a high class on only 

 one side. 



Marriage of Like to Like. 



In each class of society there is a strong tendency to intermarriage, 

 which produces a marked effect in the richness of brain power of the 

 more cultured families. It produces a still more marked effect of 

 another kind at the lowest step of the social scale, as will be painfully 

 evident from the following extracts from the work of Mr. C. Booth 



