262 RAYMOND PEARL 



left this out of account was really not 'systematic' at all but 

 rather almost altogether haphazard. It has been repeatedly 

 shown in the body of the paper that the same proportion of daugh- 

 ters of high fecundity may be obtained from certain mothers of 

 low fecundity as can from those of high fecundity, provided both 

 sets of mothers are mated to males of the same gametic constitu- 

 tion. What gain is to be expected to accrue from selecting high 

 laying mothers under such circumstances, at least so far as con- 

 cerns the daughters? 



'Selection' to the breeder means really a S3''stem of breeding. 

 'Like produces Uke,' 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 inherit- 

 ance. 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 in the present case, a 

 character is not inherited in accordance 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 application of the simple selection system of breeding could 

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

 to insist that the prolonged application of that system is bound 

 to result in improvement. 



It seems to me that it must be recognized frankly that whether 

 or not continued selection of somatic variations can be expected 

 to produce an effect on the race depends entirely on the mode 

 of inheritance of the character selected. In other words, any 

 systematic plan for the improvement of a race by breeding must 

 be based and operated on a knowledge of the gametic condi- 

 tion and behavior of the character in which improvement is 

 sought rather than the somatic. Continued mass selection of 

 somatic variations as a system of breeding, in contrast to an intel- 

 ligent plan based on a knowledge of the gametic basis of a char- 

 acter and how it is inherited, seems to me to be very much in the 

 same case as a man who, finding himself imprisoned in a dungeon 

 with a securely locked and very heavy and strong door with the 



