1 — Maize 



East and ShulU crossed pure strains of Rhode Island 

 White Cap, a starchy corn, and Crosby sweet corn. The Fi 

 generation was starchy showing the dominance of this 

 character, but the F2 generation showed segregation of 

 starchy and sweet grains in the ratio of 3 to 1. When the 

 Fi were "selfed" the sweet grains produced sweet and 2|3 

 of the starchy grains produced ears containing both starchy 

 and sweet grains in the ratio of 3 to 1, and 1-3 produced 

 cobs producing starchy grains only. The results may be 

 represented as follows: 



Starchy x Sweet .Pi 



Starchy (Impure) Fi 



I A i ^ I 



Starchy 2 Starchy Sweet F2 



(pure) (impure) (pure) 



Similarly, these investigators found that when a purple 

 corn was crossed with a white corn, the Fi grains are purple 

 and the F2 grains develop in the ratio of three purple to one 

 white. 



Further they found that when a purple-sweet corn is 

 crossed with a white starchy corn, the Fi grains are purple- 

 starchy, and the F2 grains are in the ratio of nine purple - 

 starchy grains, three purple sweet, three white-starchy, and 

 one white-sweet — a ratio characteristic of dihybrids. The 

 actual numbers were 1861-614-548-217. 



These same investigators discovered, however, an 

 anomaly when they crossed flint with floury corn. When 

 the flint corn is used as the female, the Fi grains are flinty, 

 but when it is used as the male the Fi grains are floury, i.e., 

 they invariably show the character of the female. More- 

 over the F2 grains develop in the ratio of one flinty to one 

 floury. (See explanation in Babcock and Clausen, and 

 page 124.) 



(1) — Dr. E. M. East, Professor of Experimental Plant Morphology, 

 Harvard University, was educated at the Illinois State University, 

 v^^here he conducted some excellent researches especially in corn 

 breeding and genetics. 



Dr G H Shull (1874- ). Professor of Botany, Princeton Uni- 



versity, was educated at Antioch College and Chicago Univer- 

 sity He served for several years in the U. S. Bureau ot 

 Porestrv and Plant Industry, and in the Carnegie Institute as 

 botanical investigator. His contributions to plant genetics have 

 been valuable. 



97 



