Variation and Heredity 475 



The offspring of certain pairs of beetles showing precisely 

 the same variation in spot characters were compared. 

 The offspring of one pair transmitted the variation, while 

 those of other pairs were unable to do so, varying 

 toward the mean of the species. Blaringhem was able 

 through a variety of injuries to produce certain abnor- 

 malities of corn flowers, especially the production of 

 grains in the staminate inflorescence. This abnormality 

 was not generally transmissible, yet it was transmitted 

 in a few cases, and even the degree of transmission was 

 found to be variable. 



288. Mutation and crop improvement. The principle 

 of mutation appears to be particularly important in crop 

 improvement. Taken in conjunction with the facts of 

 alternative inheritance, subsequently discussed, it directs 

 attention to uncommon individuals and types, and to the 

 greater probability of securing permanent and immediate 

 improvement by the isolation and breeding of such forms. 



No one has contributed -more to the method and results 

 of selection work than Nilsson, the Swedish investigator, 

 whose work has been made a special study by De Vries. 

 Nilsson devoted particular attention to the cereals, and 

 his method of selection was founded upon the discovery 

 that " a protean group of types was found to constitute 

 each so-called variety. These types were seen to be differ- 

 ent from one another in a previously unsuspected degree, 

 covering a range of variability adequate to comply with 

 almost all the needs of practice." 1 



The practical success of the work of Burbank and others 

 seems to rest upon a careful search for variable forms; 



> De Vries, "Plant Breeding," p. 68. 



