Nos. 620-621] COLOR IN AVENA CROSSES 



kernel pubescent, and still another lot of smooth oats. It 

 seems that the gray oats segregate as to pubescence on 

 what may be a 1 : 2 : 1 ratio. Kegarding the yellow oat it 

 is very significant that all of them are in the smooth class. 

 That is, no yellow oats are found which are pubescent. 

 Certain ones which were found appeared yellow but 

 which proved on testing to be gray instead of yellow, so 

 that at present no true yellow oats which are pubescent 

 have been obtained out of this cross. 



From these data it seems without any doubt that yellow 

 oats in some way or another tend to inhibit the factor for 

 pubescent. It is also apparent that there is one factor 

 for pubescence which is linked with the black color fac- 

 tor. There sems to be another factor for pubescence 

 which is independent of any color factor and for this 

 reason we obtain gray oats in approximately the ratio of 

 1:2:1 so far as pubescence is concerned. Owing to the 

 inhibiting effect of the yellow oat, there are no pubescent 

 forms obtained. From this material it is clear then that 

 we are working with a fatua form which has two factors 

 for pubescence, one of which is linked with the black 

 color factor and one which is independent. More will be 

 said regarding these facts later in this paper, when an- 

 other cross will be mentioned. 



Another interesting relationship is that shown between 

 the color in the F 2 generation and the segregation as to 

 type of base. As mentioned earlier in this paper, the 

 type of base differs from the wild form which is the typ- 

 ical sucker-mouth shape while that of the cultivated oat 

 is of the typical sativa form. The satha-\\ke form is 

 dominant or partially so to the wild type. A study of 

 this and a large number of other crosses in which the 

 wild type has been used as one of the parents indicates 

 that the segregation of the base follows the 1:3 ratio, 

 wild being the recessive type. 



The relation between color and type of base for the 

 second generation plants of this cross is shown in Table 

 III. 



