50 GENETICS [BoT. Absts., Vol. VIII, 



as a whole, individual plants themselves are extremely variable. Reciprocal hybrids of 

 Raphanistrum and sativus were highly vigorous and gave comparable results under a variety 

 of conditions. Fi flowers as a rule were white, but there were exceptions, especially in later 

 blossomings. One plant had one twig white-flowering and one yellow-flowering. In later 

 blossomings some flowers were observed with two petals white and two yellow and some 

 flowers showed tinges of rose or violet at end of blooming period. Structure of silique seemed 

 to be intimately connected with color of flower and varied within wide limits on hybrid plants, 

 the limits on parents being much narrower. Sugar content was high and starch low in the 

 hybrids as in radishes, a condition contrary to that in R. Raphanistncm. In character of 

 anthocyanin radishes may be divided into 3 groups: Rose or red; violet; black, graj' or white. 

 Red X black or gray gives violet. Red X yellow gives violet, but with dissociation, which 

 indicates that yellows are themselves hybrids. Red X violet gives violet, but the author 

 considers dominance of violet here simply a matter of concentration of violet pigment, for a 

 mixture of solutions of red and violet anthocyanin gives violet solution. In F2 every possible 

 combination of parental characters occurs as regards color of flower, structure of silique, and 

 root development; but there are all sorts of intermediates, and types which appear to return 

 to those of parent are not identical with them. It is argued that this demonstrates that 

 Mendel's law is only a directive one. From her studies of Fi populations the author con- 

 cludes that law of uniformity of Fi is not absolute. She favors Naudin's idea that the 

 hybrid is a living mosaic of more or less discordant elements which may at times visibly dis- 

 sociate in Fi individuals. She argues that everything connected with life is mobile and 

 changing and that it is practically impossible to generalize from particular bases. Mendel's 

 law does not, therefore, approach the validity of a mathematical law. — R. E. Clausen. 



324. RoBB, William. Plant breeding experiments at the University of St. Andrews 

 (Conductedby the late John H.Wilson). Scottish Jour. Agric. 3: 391-402. 2 pi, 2 fig. 1920. 

 — Dr. Wilson was responsible for the establishing of extensive plant-breeding experiments in 

 Scotland. The accomplishments of the last four years preceding his death have not been 

 previously published. During these years he grew many thousands of hybrid potato seed- 

 lings and had reduced his stocks to 240 selected varieties. In a cross of Sandy and Golden 

 Rain oats the Fi and F2 plants all had more or less one-sided panicles while both parents have 

 open spreading panicles. In the F2 progeny of a cross between Daubeny and Huskless oats 

 were types with two awns to the spikelet and an articulation suggestive of the wild oat, 

 Avenafalua. — H. V. Harlan. 



325. Roberts, E. A note on inheritance of polydactylism in cattle. [Abstract.] Anat. 

 Rec. 20: 211. 1921. — A normal bull mated to a polydactylous cow produced a polydactylous 

 female. This daughter produced, from matings to a normal bull, 3 calves all of which showed 

 the polydactylous condition. — E. Roberts. 



326. Roberts, Herbert F. Yellow-berry in hard winter wheat. Jour. Agric. Res. 18 : 

 155-169. 3 fig. 1919.— See Bot. Absts. 6, Entry 32. 



327. Robertson, W. R. B. Further studies on inheritance of color in the turkey. [Ab- 

 stract.] Anat. Rec. 20: 213-214. 1921.— The pattern of the black variety is allelomorphic 

 to the pattern of the bronze. Black is almost, not entirely, dominant, there being usually 

 about 6 bronze feathers widely distributed. Fi black (bronze) cT back-crossed to his bronze 

 dam gave 50 per cent of F2 bronze and 50 per cent black. An Fi black (bronze) 9 by a 

 bronze cf gave the same result. The bronze of F2, mated inter se, gave only bronze, the Fi 

 blacks gave black and bronze. — Black is likewise allelomorphic to the bourbon red and the 

 Narragansett patterns. A bourbon red 9 by the Fi black (bronze) c? gave 50 per cent 

 bronze-red intermediates, like Fi of the bronze by red cross, and 50 per cent a rusty black. 

 An Fi black (bronze) 9 by a bourbon red c? gave 50 per cent bronze-red intermediate and 

 50 per cent rusty black. The latter shows a slight trace of barring with white in the pri- 

 maries. A Narragansett 9 by an Fi black (bronze) cf gave 50 per cent black and 50 per 



