738 EXPERIMENT STATION EECORD. [Vol. 37 



Histological examinations of the developing ovary and glumes and of the 

 mature seed suggest a possible explanation for the color peculiarities of dis- 

 tinct somatic variations and for the Inheritance of some and the noninheritance 

 of others. The change from variegated to near-self seeds associated with little 

 change in the color of the glumes is thought to occur only in subepidermal cells 

 and consequently may be inherited, while the change from variegated to dark- 

 crown variegated seeds accompanied by self-colored glumes is thought to be 

 limited to the epidermal layers and hence incapable of inheritance. 



These results are thought to favor the idea that single allelomorphic factors, 

 rather than two or more closely linked factors, are responsible for the color 

 pattern of both glumes and pericarp. 



" The phenomena studied are held to have an important bearing on the ques- 

 tion of unit-factor constancy. The existence of the series of at least nine or 

 ten multiple allelomorphs to which variegation belongs indicates that a factor 

 for pericarp color has mutated several times. Some of the factors of this 

 series have not been observed to mutate, while others have mutated rarely, and 

 still others many times. In fact, tlie principal difference between certain of the 

 factors is thought to lie in their relative frequencies of mutation. It is sug- 

 gested that data such as is here presented may help to explain the somewhat 

 diverse results of selection experiments within pure lines, clonal lines, and the 

 like." 



Contribution to the study of cotton production and its future, J. V. Natta 

 Maglione {Bol. Min. Agr. [Argentina], 20 (1916), No. 7-8, pp. 6Sl-6^6, figs. 8).— 

 This is a general discussion of cotton production in Argentina. The cost of pro- 

 duction is estimated and presented In tabular form. 



Studies on oat breeding. — V, The Fi and Fj generations on a cross between 

 a naked and a hulled oat, J. Zinn and F. M. SruF.^cE (U. S. Dcpt. Agr.. Jour. 

 Agr. Research, 10 {1911), No. 6, pp. 293S12. pis. 9).— In continuing work at the 

 Maine Experiment Station previously noted (E. S. R.. 35, p. 831; 36. p. 834), 

 the authors describe in detail a white naked oat. Arena sativa nuda var. iner- 

 mis, and a black-hulled oat, A. sativa patula var. Victor, and the F, and F> 

 generations of a cross between the two. The Victor oat was the female parent, 

 and the naked oat the male parent, the F, progeny consisting of 11 hybrid 

 grains, only 4 of which germinated when planted in 1915. The Fj generation 

 comprised 854 plants, all of which, together with the Fi generation, were ex- 

 amined for hull character, grain color, pubescence at the base of the grain, and 

 inheritance of awns. 



The hulled parent was characterized by the presence of firm flowering glumes 

 which adhered clo-sely to the caryopsis, biflorous spikelets, black color of 

 glumes, strong awns, and a long but rather sparse pubescence at the sides of 

 the base of the lower grain. The naked parent was characterized by loose, 

 membranous flowering glumes which did not adhere to the caryopsis, multi- 

 florous spikelets. white or light yellow glume color, almost total absence of 

 awns, and the absence of pubescence. It is suggested that the absence of awns 

 and of pubesence may be due to the inability of these characters to express 

 themselves on the thin membranous glumes. 



The Fi generation is described as distinctly intermediate in mo.st characters. 

 In regard to the glumes, both naked and firmly-hulled grain and intermediate 

 forms were found on the same panicle and even in the sance spikelet. The 

 spikelets near the top of the panicle were entirely naked, or nearly so, while 

 those near the base of the panicle tended to be firmly hulled. A similar but 

 less marked relation was observed between the spikelets near the tip and base 

 of each whorl. 



