No. 624] INHERITANCE OF IIULL-LESSNESS 



7 



In another cross Gaines found 77.1 per cent, hulled to 

 22.9 per cent, hull-less, which caused him to conclude that 

 the two crosses were not similar in their behavior. This 

 would seem to be the case from the data at hand, yet in 

 1914 Gaines made a number of other crosses, among 

 which according to the pedigree numbers is another one 

 between these two sorts, Black (Wash. No. 665) and 

 Hulless (Wash. No. 680) which gave, this time, results 

 very similar to all the other crosses reported as made 

 that year, which indicated a 1:2:1 ratio. Gaines did not 

 offer any explanation as to the different behavior of these 

 two crosses between the same two sorts. 



From these experiments Gaines concludes, 



the percentage of hulled type suggests a simple Mendelian recessive 

 although in every ease there are a few too many hulled plants. The 

 percentage of hull-less plants is not only very irregular in the different 

 crosses but is also irregular in the different families within the same 

 cross with the exception of the two families of Sixty Day X Hull-less, 

 which gave a ratio approaching 1:2:1. The intermediate types showed 



tained with every degree of hull-lessness between these extremes. How- 

 ever, most of the intermediates produced more than half hulled oats. 

 A curve fitted to these intermediate variations in Black Tartarian 

 X Hull-less shows larger numbers at either extreme and few numbers 

 showing per cents, of hulled oats ranging from 30 to 50. This is just the 

 opposite of what we would expect if the hull-less character was caused 

 by a single Mendelian unit which produced an intermediate in the F^. 



In a paper by Zinn and Surface^ results are given of 

 a cross between a hull-less and hulled oat. The sorts 

 used were Avena sativa patula var. Victor, and Avena 

 sativa nuda var. inermis. The results indicate that their 

 forms agree very closely with those reported by Norton 

 and Gaines. The following paragraph gives part of 

 their conclusions. 



The F, generation is distinctly intermediate in most characters. In 

 regard to the glumes, both naked and firmly hulled grain as well as in- 

 termediate forms are found on the same panicle and even in the same 

 Journal of Agricultural ^Research, Vol. X, No. 6, pp. 310-311, 1917. 



