Heredity 207 



Mendel reports one instance in which the ratio in seed- 

 shape was 21 to 1, and another of 1 to 1. He also reports 

 instances of seed-color of 32 to 1, and 1 to 1. It has been 

 said that, because of Mendel's work, we shall be able to 

 produce hybrid varieties with the same certainty that we 

 produce chemical compounds. Now, a plant is made 

 up of many combinations of many units, and these com- 

 binations are the results of mathematical chance or prob- 

 ability. Of course, when the offspring are numerous, 

 all possible combinations are likely to occur; but these 

 occurrences are essentially fortuitous. Chemical com- 

 pounds are specific entities in which the parts combine by 

 necessity with definiteness. The comparison is fallacious 

 and the conclusion unsound. 



We must remember that there are whole classes of cases 

 of plant-breeding that do not fall under hybridization at 

 all. Granting the de Vriesan view that selection is incom- 

 petent to produce species from individual fluctuations, it 

 is nevertheless well established (and admitted by de Vries) 

 that very many of our best cultural varieties have been 

 brought to their present state of perfection by means of 

 selection; and by selection they are maintained in their 

 usefulness. Selection will always be a most important 

 agency in the hands of the gardener and the plant-breeder 



