IIO ANALYSIS OF THE FOUR PRINCIPLES. 



ished one-eighth. In the second generation the result will be quite 

 different; for variations 2 and 4 already constitute two-thirds of the 

 whole number of pure-breeds. 



Second Generation Pure-breeds. 



Of variation i ........ 250 



Of variation 2 . . . . . . . T , ooo 



Of variation 3 ........ 444 



Of variation 4 ........ 1,776 



3,470 

 In this generation the decrease is only 28 individuals, or about ~. 



Third Generation Pure-breeds. 



Of variation i . . . . . . . . 125 



Of variation 2 . . . . . . . i , ooo 



Of variation 3 . . . . . . . . 296 



Of variation 4 . . . . . . -2, 368 



3,789 

 In this generation there is an increase of 3 1 9 individuals, or a little 



over ~. 



Fourth Generation Pure-breeds. 



Of variation i . . . . . . . 62 



Of variation 2 . . . . . . . i , ooo 



Of variation 3 ........ 198 



Of variation 4 . . . . . . . . 3, 156 



4,416 

 In this generation there is an increase of 627, or of nearly-^. 



Tenth Generation Pure-breeds. 



In variation i . . . . . . . . 0.98 



In variation 2 . . . . . . . i , ooo 



In variation 3 . . . . . . . . 16 



In variation 4 ........ 17,758 



i8,775 

 Var. 4, of Tenth Generation = 1,000 (i.3333j) 10 computed by logarithms. 



We therefore observe that in the tenth generation variation i has 

 become less than i, and variation 4 has become the predominant type. 



For the next ten generations the average positive segregation will be 

 advanced, (i) by the preponderance of variation 4, and (2) by the 

 fact that the new variety occurs in much larger masses than at the 

 beginning of the computation, and will therefore be less exposed to 

 cross-fertilization. 



Now that the mass of pure-breeds is increased more than fourfold, 

 it is reasonable to suppose that the ratio of pure-breeding advances. 



