Nos. 620-621] COLOR IN AT EN A CROSSES 



383 



obtained from crossing two black oats which by those 

 studying classification of varieties of oats have been 

 classed as the same variety and exhibit the same general 

 botanical characters. When these two forms were 

 crossed, both being black, the first generation plants were 

 black but when the second generation was grown it was 

 found that a segregation was obtained, giving 15 black 

 to 1 non-black. This point then illustrates the statement 

 made above that we shall probably obtain different segre- 

 gations even though we are supposed to be using the same 

 variety. This is also brought out by the fact that from 

 the wild form, Avena fatua, we have been able to obtain 

 different types so far as pubescence is concerned. How 

 many other types may exist in the wild form of fatua we 

 do not know, but experiments are underway to deter- 

 mine whether it is not possible to find other types as re- 

 gards color and certain other characteristics. 



From what is here said we do not intend to convey the 

 idea that yellow color as found in oats will inhibit the pro- 

 duction of awns, pubescence and base but mean merely 

 that the yellow as exhibited in this series does that. In 

 fact, we know from the crosses we have already studied 

 where other yellow forms have been used that it is pos- 

 sible to obtain the yellow pubescent form and yellow ones 

 with the wild base. Therefore, the statements made here 

 hold only for the particular cross here reported. 



Conclusion 



The studies here presented show that we have some re- 

 lation between these yellow oats and the absence of amis, 

 pubescence, and the wild base. We also find that there 

 are two types of pubescence, or better stated, two factors 

 for pubescence, one of which is linked with black and one 

 which is independent of any color factor. Owing to the 

 inhibitory effect, we do not get a definite Mendelian ratio 

 from these studies. It is also clear that the 'third gen- 

 eration material tends to substantiate the conclusion ar- 

 rived at from the study of the second generation plants. 



