74 



Trans. Acad. Sci. of ISt. Louis. 



the fact that the first horse capable of making this speed had 

 already appeared. Horses who are by their owners known to 

 be capable of breaking the record, are much more likely to be 

 held back for advantageous conditions, than a horse of the 

 same class would be after this speed has^become a common one. 



The effect of ball bearings, the pneumatic tire and the 28- 

 inch wheel was to produce a sudden change in speed in 1892, 

 but this is an effect that must and should be considered a part 

 of the problem. The old high-wheeled sulky was also con- 

 tinually being improved, between 1850 and 1890. The inter- 

 esting fact remains that the record to-day is within a second 

 of that predicted twenty years ago. 



The results here given also seem to be sufficient to estab- 

 lish another confirmation of a general principle of evolution. 

 It would seem that each horse goes through during the few 

 years of its track life, the same kind of evolution that its 

 race goes through during the centuries. The same equation 

 which represents the result of training the individual horse, 

 represents also the supreme result of selection, breeding and 

 training of the family. 



Just as this paper is going to press, the world's record of 

 the running horse has been lowered by Alan-a-Dale^ to 

 5== 97.6 (1: 37.6). This, in connection with the well-known 

 record of Legal Tender in 1865 and of Ten Broeck in 1887, 

 will give the basis for a fair determination of the final limit 

 of the running horse. The observed speeds are given in the 

 following table : — 



The values of speed .in the fourth column are computed 

 from the equation 



log (s — 91.5)= 1.097 — 0.0082^ 



-0.0189< 



or 5 = 91.5 -I- 12. 5e 



