Inconstancy of Improved Races 111 



given for the test of the corn. The progression 

 and regression were found to be proportionate 

 to the amount of the deviation. The progres- 

 sion of the average was one-third, and the re- 

 gression in consequence two-thirds of the total 

 deviation. The amelioration is thus seen to be 

 nearly, though not exactly, the same as in the 

 previous case. 



From the evidence of the other correspond- 

 ing experiments, and from various statistical 

 inquiries it seems that the value of the pro- 

 gression is nearly the same in most cases, irre- 

 spective of the species used and the quality con- 

 sidered. It may be said to be from one-third to 

 one-half of the parental deviation, and in this 

 form the statement is obviously of wide and 

 easy applicability. 



Our figures also demonstrate the great pre- 

 eminence of vegetative varieties above the im- 

 proved strains multiplied by seeds. They have 

 a definite relation. Asexually multiplied 

 strains may be said to be generally two times 

 or even three times superior to the com- 

 mon offspring. This is a difference of great 

 practical importance, and should never be lost 

 sight of in theoretical considerations of the pro- 

 ductive capacity of selection. Multiplication by 

 seed however, has one great advantage over 

 the asexual method ; it may be repeated. The 



