No. 520] 



MENDELIAN PHENOMENA 



223 



are responsible for red, but, there being a deficiency in 

 only one of them, we get the phenomena considered in 

 Table I. 



TABLE III 



Bateson's Matthiola Crosses 



P = factor for purple. and B, produce red when present in greater 

 proportion than 90 per cent, of normal amount in pure purples. 



CO 22 ; 20 22 22 g \ 22 22 j 11 



DD 18 18 \ 18 18 'I 16 18 | 18 



In the cross now under consideration we must assume 

 that, taking the cream and the white races collectively, 

 there are deficiencies in two substances necessary for the 

 production of the red, as well as in the substance neces- 

 sary for the production of the purple, or in one of the 

 substances if more than one is necessary. 



• Let R l represent the first factor for red, R 2 the second 

 factor for Bed, and P the factor for purple. It is as- 

 sumed that when either R x or R 2 is deficient to the amount 

 of 10 per cent, of the amount of these substances found 

 in pure purple races, the reactions will not reach the 

 stage necessary for the production of red color, and that 

 when there is a like deficiency in the substance necessary 

 for transforming red into purple this transformation 

 does not occur. 



Column 2 of Table III shows the contribution of each 

 of the cell organs to the substance R r in the cream va- 

 riety; the next column gives similar data for substance 

 R 2 , and the next for the purple factor. The facts indi- 

 cate that there is a deficiency in one pair of chromosomes 

 (AA) for the substance R x in the cream variety; also for 



