DEFINITIONS 15 



it not the expression of a predetermined inheritance in a more 

 or less predetermined environment ? " 



Definitions of " Heredity." — It may be of interest to give a 

 few samples of definitions : 



" The word ' Heritage ' has a more limited meaning than ' Nature,' 

 or the sum of inborn qualities. Heritage is confined to that which 

 is inherited, while Nature also includes those individual variations 

 that are due to other causes than heredity, and which act before 

 birth." — Francis Galton, Natural Inheritance, 1898, p. 293. 



" Heredity is the law which accounts for the change of type 

 between parent and offspring, i.e. the progression from the racial 

 towards the parental type." — Karl Pearson, The Grammar of 

 Science, 1900, p. 474. 



" Under heredity we understand the transference to the offspring 

 of qualities of the parent or parents." — T. H. Montgomery, Jr., 

 Proc. American Phil. Soc. xUii. 1904, p. 5. [But the line of descent 

 is from germ-cell to germ-cell. The parent is the custodian or 

 trustee of the germ-cells rather than their producer. It is too 

 metaphorical to speak of the " parent transferring qualities to the 

 offspring." The hereditary relation includes the occurrence of 

 variations as well as the reproduction of likenesses. And what 

 are the offspring apart from their inheritance ?] 



" ' Heredity ' is most usually defined by biologists as referring 

 generally to all phenomena covered by the aphorism ' like begets 

 like.' In this sense it denotes, inter alia, the phenomenon of the 

 constancy of specific or racial types and of sexual characters ; a 

 character may be said to be inherited when it always, in one genera- 

 tion after another, is one of the characters of the species, of the 

 race, or of the one sex of the race, as distinct from the other. The 

 species, race, or sex, so to speak, ' begets its like ' as a whole. But 

 then a further question remains ; even if the type of the race is 

 constant, do individual types within the race beget their like ? 

 In so far as any individual diverges in character from the mean of 

 the race, do his offspring tend to diverge in the same direction, or 

 not ? It is to this question that statisticians have confined them- 

 selves, and they speak of a character being ' inherited ' or not 

 according as the answer to the question is yes or no — they deal 

 solely with what we may term ' individual heredity.' " — G. Udney 

 Yule, 1902, p. 196. [Biologists are as much concerned with individual 



