MENDEL'S LAW 



17 



four corners of the diagram. Thus, again, Mendel's 

 hypothesis is consistent with the observed phenomena. 



The case in which the original parents differed in 

 three pairs of characters could be dealt with in a similar 

 manner, but the diagram becomes too complicated to 

 be useful. 



Mendel's experimental proof is as follows : As the 

 hypothesis had reference to the hybrids' constitutions, 

 that is to the materials they carried, it was necessary 

 that hybrids should be employed in the experimental 

 proof, and, as their constitutions were hypothetical, it 

 was also necessary that they should be mated with 

 true-breeding plants whose constitutions were known. 

 Hybrids, therefore, similar to those produced by the 

 experimental parents differing in two pairs of characters 

 were chosen and mated first with one and then with the 

 other of their true-breeding parent kinds. That is to 

 say : hybrids between parents having round seeds and 

 yellow albumen and others having wrinkled seeds with 

 green albumen were mated first with the one and then 

 with the other parental kind. 



The following scheme should represent the materials 



