302 



Journal of Agricultural Research 



Vol. X, No. 6 



question. So far as the segregation in Fg is concerned, it can be well 

 explained by assuming one pair of genes. The heterozygous condition 

 of these genes is represented by the intermediate plants, while the 

 plants with typically hulled and typically naked grain represent the 

 respective homozygous condition. From the detailed description of the 

 intermediate plants it will be clear that neither gene is truly dominant. 

 In general appearance the intermediate forms more nearly resemble the 

 hull-less parent. 



Table II shows a good agreement between the observed and the 

 expected results. All the intermediate forms are here grouped in one 



class. 



Table II. — Segregation in regard to the hull character 



Observed. 

 Expected . 



HuUed. 



221 



213-5 



Interme- 

 diate. 



404 

 426 



Naked. 



229 

 213-5 



The inheritance of this character thus exhibits a Mendelian behavior, 

 which is known as the Zea type, after Correns. This condition is anal- 

 ogous to that presented by the base of the lower grain in the cross between 

 a wild and a cultivated oat (6) and by the character of awning in the cross 

 between certain bearded and beardless wheats (i, p. 1 57-159; 3)- The 

 question whether the inheritance of the hull character of the present cross 

 will follow the pure Zea type or the intermediate modification of that 

 type established by Von Tschermak (9, p. 85 ; 10, p. 364), for the hull char- 

 acter of barley can not be solved until the data for the third generation 

 are available. 



B. — GRAIN COLOR 



The segregation in regard to the grain color presents a simple Mendelian 

 ratio. As already stated, the F^ plants show a dominance of the pigment, 

 even though it does not possess the intensity of the color of the Victor 

 grain. In the second generation there is also a group of plants showing 

 a light-brown color of the grain, but the intensity of the pigment grades 

 from the light-brown color over brown to dark brown and black when a 

 condition similar to that of the black parent is reached. Grouping all 

 plants with pigmented grain into one class, we obtain the following ratio : 



Observed Black : White = 646 : 208. 



Expected Black : White= 640.5 : 213.5. 



As will be noted, the observed results agree very well with the expected 

 on a monohybrid ratio. 



It will next be of interest to determine whether there is a relation be- 

 tween the factors controlling the hull character and the color genes. In 

 Table III all the intermediately hulled forms are grouped in one class. 



