No. 520] 



MENDEL1AN PHENOMENA 



219 



of three red to one white. Table I shows an explanation 

 of the Mendelian results on the assumption that every 

 organ in the cell is concerned in color development. It is 

 assumed in this instance, merely for purpose of illustra- 

 tion, that when the amount of enzyme present in the cell is 

 85 per cent, or more of the amount found in pure red races 

 the oxidation process reaches the stage necessary to pro- 

 duce red coloration. The same end results would occur 

 if, because of some peculiarity of a sinr/le pair of chromo- 

 somes in the white race, as compared with the red, the 

 end result of the oxidation process in the white race gives 

 no color. 



In the first column of this table Cy represents the cyto- 

 plasm, and, in fact, all of the organs in the cell except the 

 paired chromosomes. AA, BB, etc., represent pairs of 

 homologous chromosomes. The second column gives as- 

 sumed relations between the amount, say, of the enzyme 

 produced by the different organs of the cell in the pure 



of the cell except the chromosomes produce 25 per cent, of 

 this enzyme. The first pair of chromosomes produce 15 

 per cent., the second pair .'50 per cent., and so on. 



Now, with the assumptions made, a white race would re- 

 sult if a single pair of chromosomes produce markedly 

 less of the enzyme than they produce in the red race. 

 Column 3 shows the hypothetical conditions in such a 

 white race. In the table it is assumed that in the red race 

 the second pair of chromosomes produce 30 per cent, of 

 the total amount of enzyme present, while in the white 

 race, for some reason, this pair of chromosomes produces 

 only one third of the enzyme it does in the red. Thus, in 

 the white race we have only 80 per cent, of the amount of 

 enzyme present in the red, and not enough to carry the 

 oxidation process to the point of giving red coloration. 

 The hybrid between these two races will have one chro- 

 mosome producing its 15 parts and another c 

 producing only 5 parts, thus giving 20 parts where in the 

 red race we had 30. In all, there is in the hybrid 90 per 



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