No. 552] INHERITANCE OF FECUNDITY 709 



The Selection Problem 

 The results of the present investigation have an inter- 

 esting and significant bearing on the earlier selection ex- 

 periments on fecundity at this station. It is now quite 

 plain that continued selection of highly fecund females 

 alone could not even be expected to produce a definite 

 and steady increase in average flock production. The 

 gametic constitution of the male (in respect especially to 

 the L 2 factor) plays so important a part in determining 

 the fecundity of the daughters that any scheme of selec- 

 tion which left this out of account was really not " sys- 

 tematic " at all, but rather almost altogether haphazard. 

 It is repeatedly shown in the detailed account of these 

 experiments that the same proportion of daughters of 

 high fecundity may be obtained from certain mothers of 

 low fecundity as can be obtained from those of high fe- 

 cundity provided that both sets of mothers are mated to 

 males of the same gametic constitution. What gain is to 

 be expected to accrue from selecting high laying mothers 

 under such circumstances, at least so far as concerns the 

 daughters ! 



" Selection " to the breeder means really a system of 

 breeding. " Like produces like," and " breed the best 

 to get the best "; these epitomize the selection doctrine 

 of breeding. It is the simplest system conceivable. But 

 its success as a system depends upon the existence of an 

 equal simplicity of the phenomena of inheritance. If the 

 mating of two animals somatically a little larger than the 

 average always got offspring somatically a little larger 

 than the average, breeding would certainly offer the 

 royal road to riches. But if, as a matter of fact, as m 

 the present case, a character is not inherited in accord- 

 ance with this beautiful and childishly simple scheme, 

 but instead is inherited in accordance with an absolutely 

 different plan, which is of such a nature that the appli- 

 cation of the simple selection system of breeding cou d 

 not possibly have any direct effect, it would seem idle to 



