Tlie Mendelian Inheritance of Certain Chemical Characters in Maize. c 



plot was in an isolated locality far removed from other corn, and 

 in a situation such that in addition to distance natural barriers acted 

 to prevent the entrance of foreign pollen. No attempt was made to 

 control pollination within the plot, so that what happened was a 

 free and general crossing of the F^ plants inter se. Since the original 

 parents were a white sweet and a yellow starchy corn the Mendelian 

 expectation here is that the Fg kernels resulting from the free and 

 random intercrossing of Fj gametes will be of four different kinds 

 (viz. yellow starchy, white starchy, yellow sweet and white sweet) 

 in the ratio of 9:3:3:1. This is apparent if the gametic formulae 

 be worked out. 



Let Y - yellow endosperm 



y = absence of yeUow = white endosperm 

 S = starchy endosperm 

 s = sugary endosperm i). 

 Then in the P generation we have 



YS'YS = yellow dent (starchy) parent 

 ys-ys = white sweet parent. 

 When crossed these give in Fj 



YS-ys ^ yellow starchy Fj kernels, there being domi- 

 nance of the YS characters. 

 These F, kernels produce plants which make gametes of the 

 following kinds: YS, Ys, yS, ys. 



These mated at random give F.j kernels of the following sorts: 

 2 YS-Ys 



2 YS-yS 

 2 YS-ys 

 2 Ys-yS 

 I YSYS 



1 ya-yo 1 ^,^ ^ white starchy 



2 yS-ys J 



9 vellow starchy i ys-ys =1 white sweet 

 lYs-Ys 

 2 Ys-ys 



3 yellow sweet. 



As a matter of fact extensive counts gave a reasonable approxi- 

 mation to the expected 9:3:3:1 ratio. Fig. iC shows an ear bear 

 ing Fo kernels. The corn on Dr. Smith's farm made a good growth 

 but owing to seasonal and cultural conditions matured rather une- 

 venly. After it was harvested a sample of about two bushel of ears 

 was sent to the Station. This was a random sample of the crop. 

 Over 50 of these ears (taken at random) were shelled and the kernels 



1) We will not stay here to consider what it is that s denotes the absence of. 

 Let us for the moment regard the notation as merely a symbolic expression of the 

 observed fact, without ulterior implications. 



