NAUDIN MENDEL'S FORERUNNER 87 



productive varieties, and Naudin (1862) in France who 

 made a comprehensive survey of the facts of hybridization 

 in plants and came very near to expressing the generalization 

 which Mendel reached four years later. He pointed out the 

 significance of the fact first observed by Kolreuter that hy- 

 brids may be brought back to the form of either parent by 

 repeated crossing with that parent. Naudin supposes that 

 the potentialities of each species are contained in its pollen 

 and ovules and the potentialities of both species are present 

 together in the hybrid. If species A is fertilized by species B, 

 the hybrid contains potentialities AB. Naudin supposes 

 that these potentialities may segregate from each other in 

 the pollen grains and ovules of the hybrid plant. An ovule 

 A of such a hybrid plant, if fertilized by pollen of the pure 

 species A, will form a plant of exactly the same nature as 

 pure species A. This idea of the segregation of potentialities 

 in the germ-cells of the hybrid was adopted by Mendel. He 

 added to it the conception that the segregation applies to 

 single potentialities or characteristics rather than to all the 

 potentialities of a species at once, and the result is what we 

 call Mendel's law. Like all great discoveries it was not made 

 out of hand, nor as the result of one man's work alone. 

 Mendel added one final touch to the work of his predecessors 

 as summarized by Naudin, and the result was that hybridi- 

 zation became for the first time an orderly and understand- 

 able process, capable of throwing light on normal heredity. 



