THE. FOUNDATIONS OF ZOOLOGY 



In his earlier writings Galton, borrowing, I suppose, from " The 

 Tempest," uses the word nurture to designate what is commonly 

 called acquired characters, and this term is so apt and expressive 

 that it should not be permitted to pass out of use, for it may be 

 given a definite technical meaning without violence to its ordinary 

 use. Using nurture instead of acquired characters for the influence 

 of the environment of the individual, we may speak of the two 

 elements of breeding as ancestry and nurture. 



It is obvious at the present day that our studies of inheritance 

 can have little value unless we distinguish between these two 

 factors ; for many naturalists hold that there is good ground for 

 asking whether the effects of nurture are ever inherited, and most 

 naturalists admit that it is possible that the value of these two 

 elements in breeding may be very different 



If breeding is to be studied by the statistical method, for the 

 purpose of exhibiting the laws of inheritance, we must employ 

 types in which we can separate the effects of ancestry from the 

 effects of nurture ; for if we make use of types which do not admit 

 of this analysis, our results may tell us no more of inheritance than 

 the scheme of prices tells us of the value of blood in horses. 



If, as many teach, inheritance is the equivalent to ancestry, 

 and nurture is never inherited, no type in which these two factors 

 are combined can tell us anything about inheritance. 



It seems probable to me that the resemblance which Galton 

 points out between the finger marks of fraternal couples may be 

 due to nurture, in this broad sense of the word, and not to inheri- 

 tance, for there is ample evidence that the value, in breeding, of 

 a given parental characteristic does depend upon its origin, and 

 that one due to nurture has a very different value from one which 

 is itself inherited. 



Of the 2459 deaf pupils of the American Asylum, nearly 600 

 have married, and have become the parents of over 800 children, 

 of whom 104, or more than 12 per cent, were born deaf a 

 ratio which is great enough to prove that inheritance has some 

 influence. Analysis of the record shows clearly, however, that 

 these deaf children are not uniformly distributed among the 

 married pupils of the asylum, but that the result is influenced by 

 the character of the parental deafness. From 283 of the 596 



