16 A MANUAL OF MENDELISM 



two pairs of characters : one in having round seed with 

 yellow albumen while the other has wrinkled seed with 

 green. The materials offered should be : 



In the ovaries In the anthers 

 R R 



,w w. 



The materials R and w in the ovaries have equal 

 chances of combining with R or w in the anthers, and 

 equal numbers of the combinations RR, Rw, wR, and 

 WW should be formed. At the same time the materials 

 Y and g should form equal numbers of the combinations 

 YY, Yg, gY, gg. But, since the materials are distri- 

 buted concurrently and independently, the combina- 

 tions formed by one pair should be distributed equally 

 among those formed by the other. For instance, 

 among the seeds carrying the materials RR, equal 

 numbers should be found carrying the materials YY, 

 Yg, gY, and gg, and so on for the other combinations in 

 which R and w are concerned. This will be made 

 clearer by the diagram on page 17, in which the distribu- 

 tion of the R and w materials is shown horizontally and 

 that of the Y and g materials perpendicularly. 



If this diagram be examined, the action of dominance 

 being kept in mind, it will be seen that there should be 

 nine round seeds with yellow albumen, three round with 

 green, three wrinkled with yellow, and one wrinkled 

 with green. It will also be seen that there should be 

 one seed pure as to both parental characters in each of 

 the four kinds. These pure seeds are indicated at the 



