4o8 BOTANICAL GAZETTE [may 



and this effectually solved the difficulties. This is a so-called 

 corn-pollinator, a description of which has already been pub- 

 lished. 1 Even in inexperienced hands this method will not only 

 insure full pollination, but will never admit foreign pollen. Its 

 drawback lies in the fact that it lengthens the process somewhat; 

 hence it is felt that this device may be recommended to all save 

 experienced operators, who are conducting extensive experiments. 



Normal ratios 



An attempt was made to discover how exactly certain complex 

 ratios might be predicted. Material was sought in which a number 

 of factors could interact to produce various but predictable ( ?) 

 ratios. Nothing was more suitable than the set of factors involved 

 in the inheritance of aleurone color in corn. These factors have 

 already assumed an important role in pedagogy. R and C are 

 complementary factors, the presence of both being required for 

 the production of red aleurone, and P 2 is a supplementary factor 

 which changes red to purple (PRC is purple, pRC red, PrC white). 

 Other factors have been added to this set by East and Emerson, 

 but they are not dealt with in this paper. The original stock 

 material was furnished by East, to whom the writer wishes to 

 express his appreciation. 



Leaving out of consideration those well established cases in 

 which a i :o or 3 : i ratio is produced, it was found that the material, 

 as originally provided, could be manipulated to produce 8 different 

 ratios. Appropriate crosses were made, therefore, and of the result- 

 ing crop all ears containing 64 or more grains are considered in 

 the following summary. 



I. — 0:1:1 (no purple: 50 per cent red 150 per cent colorless) 

 ratio predicted; from pprrCCXppRrCC and reciprocal. Eight 

 ears gave a total of o purple : 559 red 1659 white, or an average 



1 Bot. Gaz. 58:63. 1919. 



2 East and Hayes use the symbol P for this factor, while Emerson uses Pr for 

 what is probably the same factor. 



East, E. M., and Hayes, H. K., Inheritance in maize. Conn. Agric. Exp. Sta. 

 Bull. no. 167. pp. 142. pis. 25. 1911. 



Emerson, R. A., A fifth pair of factors, Aa, for aleurone color in maize, and its 

 erlation to the Cc and Rr pairs. Cornell Univ. Agric. Exp. Sta. Mem. 16 pp. 231-289. 

 1918. 



