No. 525] SHORTER ARTICLES. AND DISCUSSION 567 



generation. The horses which were thus cut out of the first 

 selection hy the third selection, occurring some thirty or more 

 years later, Avere more largely sons of young sires than sons of 

 old sires, with the net result that those left were sons of sires 

 averaging l:$.f> years of age. 



This is the process which has been going on from generation to 

 generation — each selection reducing the number of horses in ear- 

 lier generations which are left to breed on to later generations. 

 Chester proved some years ago that all known standard trotters 

 were descended in the male line from one or another of no more 

 than seventeen foundation horses. While these all stand as hav- 

 ing been progenitors of trotters, the majority of them represent 

 what are now extinct families, so that the trotters as now bred 

 come in the male line from only six or eight horses. 



The process set forth explains how it comes about that, in 

 examining the pedigrees of any trotting stock, the further we 

 go back in those pedigrees the older the sires appear, but it does 

 not explain why a late selection cuts off young sires and pre- 

 serves old sires of earlier generations. 



That is the supreme question I am asking biologists. I have 

 asked it in several forms before without getting a reply com- 

 mensurate with what 1 consider the importance of the question. 

 It is hoped that the present form, accompanied by the explana- 

 tion upon which the form is based, will bring forth a genuine 

 effort to explain the cause of these remarkable facts. 



Casper L. Redfield. 



THE LOGIC OF CHANCE IN PROBLEMS OF GENETICS 



The literature at present appearing dealing with problems 

 of genetics and evolution teems with uncertainty and inexact- 

 ness in the use and misuse of the word 11 chance." Some definite 

 undrfstaieiin-' of t h<- significance of the concept as a legitimate 

 category of scientific reasoning seems desirable. At any men- 

 tion of the word chance, some listener is sure to rise in protest 

 with the old adage — "There is no chance, it's only your ignor- 

 ance." The acceptance or the rejection of this hit of prophecy 

 depends on the ultimate postulate of the absolute uniformity of 

 nature. The truth of this postulate is a metaphysical question 

 with which the ordinary student of genetics is not concerned. 

 He is reminded of the fact that Darwin and all after him have 



