OLD TYPES AND NEW 153 



are selected in the hope that the gains made by them 

 will be maintained in their offspring. 



We have seen that it is very questionable whether 

 acquired characters which are due to environmental 

 conditions play any role whatever in heredity. The 

 phenotypic character does not always indicate what 

 the germplasm will subsequently do, and when the 

 true genotypic constitution of the germplasm is still 

 further masked by the temporary fluctuations caused 

 by a modified environment, it is increasingly difficult 

 to select wisely from the display of variants those 

 which will produce the best ancestors for the future 

 stock. 



That this common procedure of selecting the best- 

 appearing animal in the flock and the biggest ear of 

 corn in the bin, has met with a large degree of success 

 in the past is due entirely to the fact that in many 

 instances the phenotypic character is an actual ex- 

 pression of the genotypic constitution. This is not 

 always the case, however, and we cannot now fail 

 to see that the method is blind and full of error. Its 

 successes are due to the indirect results of chance 

 rather than to a direct control of the factors of hered- 

 ity. The great proportion of failures resulting from 

 this procedure now find a reasonable explanation from 

 the standpoint of Mendelism. 



b. The Method of Rim pan 



Contrasted with the Hallet method of augmenting 

 acquired characters and then selecting the best display 

 of them, is the method of Rimpau, who experimented 



