No. 520] 



MENDELIAN PHENOMENA 



221 



narily called two pairs of Mendelian characters. Under 

 the assumptions I have made this simply means that in 

 the white race there are two pairs of chromosomes which 

 were deficient in the amount of enzyme produced as com- 

 pared with the pure red race used by de Vries in this 



In the third column of Table II we have 14 parts of en- 

 zyme instead of 30 in the second column (chromosomes 

 AA), and 22 parts instead of 26 in the second column 

 (chromosomes CC). Since the hybrid gets one of each 

 pair of chromosome from each of the parents it has 22 

 parts instead of 30, and 24 instead of 26. If, in this case, 

 the amount of enzyme present in the cell is S3 per cent., or 

 more of that present in the original red race with which 

 de Vries worked, it is assumed that the oxidation process 

 will reach the red stages. The hybrid in this case is red, 

 though perhaps not so deep a shade of red as the pure 

 red race. 



In generation F 2 of this hybrid we have nine types. 

 The first type is like the pure red race with which de 

 Vries started. The third of these types is another pure 

 race, but with a lessened amount of enzyme, and presum- 

 ably less intense red color. The seventh type is also a 

 pure race, but it is one which had only a little red at the 

 margins of the petals and a type to which de Vries gave 

 the name Delilah. The ninth type is also a pure race, 



