Tricotyloiis Races Do Not Arise by Selection. 395 



(§ 4) these two species were omitted from consideration 

 in order to describe the experiments here in their en- 

 tirety. 



The hope which I cherished at the beginning of these 

 experiments has not been fulfilled, it is true; but I think 

 that a brief notice of it will serve a useful purpose. The 

 present form of the theory of selection would justify 

 the expectation that a continued selection of the tricotyl- 

 ous individuals would result in a race which should, 

 year after year, produce tricotyls in continually increas- 

 ing quantities, until ultimately a new variety or sub- 

 species would arise, composed solely of such individuals. 

 This form of the theory is very accommodating. If we 

 have regard to the law of regression (Vol. I, p. 83), the 

 mean of the race always lags further behind the indi- 

 viduals which have been and are to be selected ; so that, 

 as a matter of fact we never attain to the type of a new 

 and constant race. But if we neglect this law, as is now 

 frequently done, w^e might expect that continual and 

 uniform progress, which alone could account on the 

 ground of the theory of selection for the origin of spe- 

 cies in the vegetable and animal kingdom. And lastly 

 we might assume an increase of variability in the chosen 

 direction by means of selection, an hypothesis wdiich, as 

 I har-e shown in the first part (p. 9), is entirely unsup- 

 ported by evidence. 



The first of these hypotheses would lead us to ex- 

 pect a variable tricotylous race, never becoming perfectly 

 constant, a thoroughbred race in the agricultural sense 

 of the word. The second would lead us to expect a con- 

 tinuous and uninterrupted increase in tricotylous indi- 

 viduals resulting in a constant tricotylous subspecies. 

 The third would point to a gradual acceleration of the 



