Apeil 17, 1914] 



SCIENCE 



683 



one modifier. It has not been assumed in the 

 above explanation that the partners in an F, 

 " factor " fuse to make a new factor. Thus 

 we have to deal in both (^ and 5 gametes pro- 

 duced by the Fj with factors 4 and 9 for each 

 of the three size factors, length, breadth and 

 thickness, occurring in equal numbers, and 

 mating by chance (in self-fertilization). This 

 is the same assumption made by Mendelians, 

 even if they should not admit the F, inher- 

 itance of a; ^ ^ab. There would be these 

 eight possible combinations uniting with each 

 other by chance: 



Combiuation Length Breadth Thickness 



14 4 4 



2 4 4 9 



3 4 9 4 



4 9 4 4 



5 9 9 4 



6 9 4 9 



7 4 9 9 



8 9 9 9 



These would result in the following 

 matings : 



Mating 

 1X1 

 1X2 

 1X3 

 1X4 

 1 X 5 

 1 X 6 

 1X7 

 1X8 



2X1 

 2X2 

 2X3 

 2X4 

 2X5 

 2X6 

 2X7 

 2X8 



3 X 1 

 3X2 

 3X3 

 3X4 

 3X5 

 3X6 

 3X7 

 3X8 



]SIating 

 4X1 

 4X2 

 4X3 

 4X4 

 4X5 

 4X6 

 4X7 

 4X8 



5 X 1 

 5X2 

 5X3 

 5X4 

 5X5 

 5X6 

 5X7 

 5X8 



6X1 

 6X2 

 6X3 

 6X4 

 6X5 

 6X6 

 6X7 

 6X8 



7X1 

 7X2 

 7X3 

 7X4 

 7X5 

 7X6 

 7X7 

 7X8 



8X1 

 8X2 

 8X3 

 8X4 

 8X5 

 8X6 

 8X7 

 8X8 



Among the possible combinations there are 

 16 in which both (^ and 5 have furnished the 

 factor for length 4, and it has been commonly 

 assumed that therefore one quarter of the F, 



