232 THE AMEBIC A\ XATLliALlST [Vol. LI 



The fourth column shows the plant numbers of the Fi 

 plants, which were self-fertilized. In addition, plants 

 (31), (32) and (34) were crossed with certain aleurone 

 testers of known constitution provided by Professor E. 

 A. Emerson. 



All the grains on the ears of plants (21), (22), (29), 

 (43), (45) and (44) were colorless. The aleurone counts 

 on the ears from purple seed are arranegd in Table VI. 



TABLE VI 



I \i ( I iiD Ears OF Plv\t irom the 



I - : ! i , V 3468 (10) 



These ratios indicate that plants (1), (3), (11), (31) and 



(33) are heterozygous for one aleurone factor only. 

 Plants (32) and (34) also contain that factor but appar- 

 ently they have in addition another aleurone factor; which 

 likewise is heterozygous because the aleurone ratios, al- 

 though they deviate somewhat from the 9:7 proportion, 

 can not be classified as 3 : 1 or 27 : 37 ratios. 



Only tests with plants of known aleurone formulae will 

 determine whether it is the C, R, or A factor that is linked 

 with G. Such tests have been made by using the aleurone 

 testers described by Emerson (1917). These aleurone 

 testers possess colorless grains in which all the aleurone 

 factors except P are homozygous. For example, the R 

 tester has the formula rrCCAAii, the C tester the formula 

 RRccAAii, and the A tester the formula RRCCaaiL In 

 Table VII are presented the data involving the various 

 tests for the aleurone factors. Plants (31), (32) and 



(34) possess all the three aleurone factors in question 



