BLASTOGENIC VARIATIONS. 123 



generations. These records were preserved by Sir 

 Everett Millais, who had originated the stock of hounds 

 some twenty years ago. The Bassets are dwarf blood- 

 hounds, of two and only two recognised varieties of 

 colour. They are either white with large blotches 

 ranging between red and yellow, or they may, in addi- 

 tion, be marked with more or less black. In the former 

 case they are technically known as " lemon and white," 

 and in the latter case as " tricolour." Transitional 

 cases between these two forms are very rare. No less 

 than 817 hounds of known colour, all descended from 

 parents of known colour, were available as material. 

 In 567 out of these 817 the colours of all four grand- 

 parents were known, and in 188 cases the colours of all 

 eight great-grandparents were known as well. It 

 was found that 79 per cent, of the parents of tricolour 

 hounds were tricolour, whilst 56 per cent, of the 

 parents of lemon and white hounds were tricolour. 

 Hence from these values the contributions of unknown 

 ancestors could easily be calculated. Working from 

 these numerous data, Galton was able to confirm en- 

 tirely his previous conclusions regarding heredity, and 

 extend them in the direction then hinted at. He proved 

 that the two parents do contribute between them one- 

 half or (0.5) of the total heritage of the offspring: 

 whilst the four grandparents contribute one-quarter, or 

 (0.5) 2 : the eight great-grandparents one-eighth, or 

 (0.5) 3 , and so on. Thus the sum of the ancestral con- 

 tributions is expressed by the series [ (0.5) + (0.5) 2 ;-f- 

 (0.5) 3 + . . . etc.], which, being equal to 1, accounts 

 for the whole heritage. The same statement may be 

 put in a different form, by saying that each parent con- 



