224 



THE AMERICAN NATURALIST [Vol. XLIV 



the purple factor in another pair of chromosomes (DD). 

 These deficiencies are italicized in the table. In the 

 white variety there is assumed to be a deficiency for the 

 substance R 2 in a third pair of chromosomes. These as- 

 sumptions give the phenomena found by Bateson. A 

 similar case is found in sweet peas. 11 



It is seen in Table III that the cream variety has less of 

 R l than is necessary to produce red coloration. It also 

 has less of the purple factor than is necessary for con- 

 verting red into purple, while the white variety has less 

 of the substance R 2 than is necessary for the production 

 of red. 



Generation F l will have enough of all these substances 

 to produce red and to convert red into purple. 



The second generation of this hybrid contains 27 types. 

 I will not here go into detail concerning that generation, 

 but will merely add that the assumptions made are con- 

 sistent with the facts observed in the second generation. 



TABLE IV 

 Heterozygote Characters 

 Spotted F 1 beans from non-spotted P^s. 



Cy 40 | 30 40 30 40 "30 



AA 36 I eg \ 16 42 ! 26 \ 32 



BB etc. 24 j 28 24 28 24 28 



_J 100 ! 80 j 80 I 100 j 90 I 90 



Table III deals with cryptomeric characters which are 

 seen to owe their development to the reaction between 

 two, or possibly more, chemical substances, the production 

 of each of which is a generalized function of the cell. It 

 is, of course, possible that each of these substances is 

 produced only by a single chromosome, which case would 

 be merely a limiting case in which all the cell organs ex- 



"Rep. Ill, Evolu. Com., Eoy. Soc. 



