io8 INHERITANCE IN ANIMALS 



I hope I have succeeded in showing you something of 

 the special difficulties associated with the study of in- 

 heritance, and in making clear to you one of the methods 

 by which experience of hereditary phenomena must be 

 recorded. I will only add a word to show you the kind 

 of general statement to which work of this kind seems to 

 lead. It seems likely that in cases where the mating of 

 parents is not determined to any serious extent by their 

 likeness or unlikeness in the character discussed, the regres- 

 sion of children on parents has a value very nearly the same, 

 and very nearly equal to \, for a large series of characters, 

 mental as well as physical, in human beings, and for a 

 large series of characters in the higher animals, at all 

 events, if not in animals generally. It seems therefore 

 likely that we shall soon be able to know with some 

 accuracy how much we can predict about any group of 

 unborn animals from a mere study of one parent. By 

 such a study, we learn some of the conditions on which 

 the characters of the young depend : if we examine both 

 parents, we learn more of these conditions ; if we study 

 not only the parents but the grandparents we learn still 

 more ; and so on. The results so far achieved make it 

 probable that Mr. Galton's original prediction will be 

 verified for the large class of cases to which he intended 

 it to apply, and that the influence of the different genera- 

 tions of ancestors, as measured by the regression co- 

 efficients between these and existing individuals, will be 

 found to diminish with the remoteness of the ancestors, 

 according to the terms of a simple geometric series, which 

 is sensibly the same at least for all those characters among 

 the higher animals which have been properly examined. 



I should transgress the limits prescribed for me if I 

 said any more about the results which seem already within 

 reach : fascinating as the subject is, I must leave you to 

 picture to yourselves, as you will easily do, the important 



