40 The Third and Fourth Generation 



determiner while in the self-fertihzed yellow- 

 seeded plant diagrammed above it has a double 

 dose; in both instances a yellow-seeded plant 

 is the product, but one has all its cells provided 

 with a single yeUow determiner, the other has 

 cells with two determiners. 



Mendel further supposed that at one-stage, 

 when the cells of the plant divide to produce 

 those cells known as the eggs and sperm that 

 are so essential in reproduction, the determiners 

 remain indivisible. It is evident that when a 

 mother-cell divides to produce two daughter- 

 cells that are to function as eggs or sperm, if 

 the mother-cell has two determiners each egg or 

 sperm may have one; if, however, the mother- 

 cell has only one determiner, the sperm or eggs 

 must be of two sorts, one with and one without 

 the determiner. The pure yellow-seeded pea 

 plant would have eggs and sperm each possess- 

 ing a determiner for yeUow (Y). The pea 

 plant resulting from a cross of the yellow-seeded 

 and the green-seeded would have eggs and 

 sperm both with and without the yellow 

 determiner and these two kinds in equal num- 



