STATISTICAL STUDY OF HEREDITY 81 



But even these are not the most complex of the 

 problems of heredity. Consider, for instance, the 

 matter of speed in racehorses. A multitude of diffe- 

 rent organs, and even certain mental characteristics, 

 are concerned. Further, the presence of certain factors 

 in the hybrid condition appears to be essential to its 

 highest development, for close inbreeding is always 

 detrimental to racing ability. The conditions of 

 development and training have an important influence 

 in the matter, and their effects are inextricably 

 mixed up with the inborn qualities. Again, we are 

 dealing with bi-parental inheritance, and this intro- 

 duces a complication. And, finally, the horse is a 

 slow-breeding animal, and one which it would be 

 scarcely possible to breed in large numbers for experi- 

 mental purposes. 



Here, then, we have a practical problem of a com- 

 plexity so great that Mendelian analysis seems out of 

 the question. And it appears probable that many 

 economic characters in animals, which have usually 

 been improved by a long process of selection, are of a 

 similar nature. 



It is, perhaps, going too far to predict the actual 

 incapacity of the Mendelian method to cope with 

 such problems, for the method is still in its infancy, 

 and one cannot foresee all its possibilities. Still there 

 seems to be a great probability that such questions 

 are too complex for Mendelian treatment. It is in 

 such cases, where many small causes operate in pro- 

 ducing a single result, that statistical methods come 

 to our aid. The coefficient of heredity for speed, 

 could it be determined, would have a distinct practical 

 value. 



We may, then, conclude that while all inheritance 

 may well be at bottom Mendelian, and while a de- 

 scription of any particular case in Mendelian terms is 

 simpler and better than a statistical result, yet the 

 latter is valuable if, or as long as, the Mendelian analysis 

 is not found possible. 



