CHAPTER IV. 



SCHEMES OF DISTRIBUTION AND OF FREQUENCY. 



Fraternities and Populations to be treated as Units. — Schemes of Distribu- 

 tion and their Grades. — The Shape of Schemes is independent of the 

 number of observations. — Data for Eighteen Schemes. — Application 

 of the method of Schemes to inexact Measures. — Schemes of Fre- 

 quency. 



Fraternities and Populations to be Treated as Units. — 

 The science of heredity is concerned with Fraternities 

 and large Populations rather than with individuals, and 

 must treat them as units. A compendious method is 

 therefore requisite by which we may express the dis- 

 tribution of each faculty among the members of any 

 large group, whether it be a Fraternity or an entire 

 Population. 



The knowledge of an average value is a meagre piece 

 of information. How little is conveyed by the bald 

 statement that the average income of English families is 

 100/. a year, compared with what we should learn if we 

 were told how English incomes were distributed ; what 

 proportion of our countrymen had just and only just 

 enough means to ward off starvation, and what were the 



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