1917] CURRENT LITERATURE 165 



Genetics of flax. — Miss Tammes 26 has made a genetical study of the flower 

 characters of 6 varieties of the common flax, Linum itsitatissimum. These 

 varieties consisted of 3 dark blue, 1 light blue, and 2 white varieties. Besides 

 the color of the flower, with which she worked chiefly, she studied the color of 

 the anthers, the color of the seeds, the shape of the petals, the color of the veins 

 in the petals, and the number and viability of the seeds produced. These 

 latter characters she finds correlated with the color of the flower and dependent 

 upon the same factors. The several varieties are described and their genetic 

 formulae given, after which the author presents in tabular form the expected 

 ratios and the observed results in the second and third generations. She 

 concludes that the blue color is the result of two complementary factors, B and 

 C. The presence of these two factors alone produces the light blue flowers, and 

 the dark blue is brought about by the action of an intensifying factor A co- 

 operating with B and C. Unless both B and C are present the flower will be 

 white. The factor A acts as an intensifier only on the light blue of the petals 

 and has no effect on the color of the anthers, on the color of the seed, or on the 

 color of the veins in the petals. The factor B is not only one of the necessary 

 factors for the production of the blue flower color, but even without the 

 cooperation of C brings about the blue color of the anthers and the brown 

 color of the seeds, prevents the crinkling of the petals which, were it not present, 

 would be caused by the presence of C, and overcomes the tendency of C to 

 lessen the number and viability of the seeds. The factor C, besides producing, 

 with B, the blue color of the flower, brings about, when in a homozygous con- 

 dition, a deeper pigmentation of the veins in the petals; and causes, when B 

 is absent, a crinkling of the petals and a lessening in the number and viability 

 of the seeds. In respect to the color of the anthers, which results from the 

 presence of B } it is pointed out that although the 6 varieties studied are in 

 agreement with the interpretation given, there is a variety, which has not yet 

 been studied, that has blue flowers and yellow anthers. As this is contrary to 

 the conclusions arrived at from the 6 varieties investigated, the author suggests 

 that the factor B may be, not a single unit, but a complex, with some essential 

 part or factor lacking in the variety with blue petals and yellow stamens. On 

 the other hand, B may be a unit and the blue anthers may be lacking because 

 some other necessary factor besides B is lacking in that variety. An investi- 

 gation of this problem is promised. — Ben C. Helmick. 



Physiological temperature and moisture indices. — In extending his studies 

 of the derivation and use of indices of temperature in relation to plant growth, 

 Livingston 2 ? distinguishes 3 classes of such indices. The first is the sum- 



26 Tammes, Tine, Die genotypische Zusammensetzung einiger Yarietaten der- 

 selben Art'und ihr genetischer Zusammenhang. Extrait Recueil Trav. Bot. Xeer- 

 land. 12:217-278. 1915. 



3 7 Liyixgston, B. E., Physiological temperature indices for the study of plant 

 growth in relation to climatic conditions. Physiol. Researches 1 : 399-420. figs. 4. 1916. 



