118 GENETICS [Bot. Absts., Vol. IV, 



721. Riviere, G., and G. Bailhache. L'Amygdalopsrsica Formonti. Compt. Rend. 

 Acad. Sci. Paris 168: 525. 1919. — This graft hybrid produced a fertile seed from which was 

 grown a shrub, now three years old, which exhibits solely the characteristics of an almond 

 particularly in regard to its leaves. Three more fertile seeds were produced in 1917 on the 

 spontaneously arisen almond branches. These have also produced young vigorous almond 

 trees. — E. B. Babcock. 



- 



722. Roberts, Herbert F. A Darwinian statement of the Mendelian theory. Nature 

 103: 463-464. Aug. 14, 1919. — Extracts from "Animals and plants under domestication;" 

 explanation of reversion in F 2 through recombination of dormant grandparental gemmules. — 

 Merle C. Coulter. 



723. Roberts, Herbert F. A demonstration of the coefficient of correlation, for ele- 

 mentary students of plant breeding. School Sci. and Math. 19:619-628. 6 fig. 1919. — A 

 demonstration of the meaning of the correlation coefficient. A geometric and trigonometric 

 explanation is given. "The value of the correlation coefficient is always the value of the 

 tangent of the angle which the correlation line forms with the axis of X, where it passes 

 through the point of intersection of the axes X and Y." The numerical relation between the 

 tangent and correlation coefficient is shown. The illustrations and discussions will bring 

 out more forcibly the meaning of the correlation coefficient. — H. H. Love. 



724. Roberts, Herbert F. An improved colorimeter for color inheritance study. Plant 

 World 22:262-269. 4 fig- Sept., 1919. — Author describes (using construction diagrams) 

 improvement on a common tintometer, to make it more readily available to geneticists. Most 

 important change is addition of mechanism for revolving colored material to eliminate effects 

 of inequalities of surface. Recommends use of artificial light and ascertaining by voltmeter 

 that current for it is constant. — James P. Kelly. 



725. Rosendahl, C. O. Variations in the flowers of Erythronium propullans Gray. Tor- 

 reya 19: 4347. 3 fig. Mar., 1919. — Stamens 2 to 6, mode 4; perianth segments 4 to 6; mode 

 4; taxonomic relatives fairly constant 6 in both cases. [See Bot. Absts. 3, Entry 340.] — Merle 

 C. Coulter. 



726. Russell. Alice Mary. The macroscopic and microscopic structure of some hybrid 

 Sarracenias compared with that of their parents. Contrib. Univ. Pennsylvania Bot. Lab. 5: 

 341. PI. 1-5. 1919. — The writer finds that the hybrid forms of Sarracenia studied in com- 

 parison with their parents are intermediate in relation in almost all details. This is shown in 

 the size of the plants, in the shape of the pitchers, in the blending of the placental lid shapes, 

 in the matter of coloring, in the matter of the size and shape of the flowers (especially petal 

 shape and size), in the odor, etc. All of the above examples of the blending of parental char- 

 acters can be seen with the naked eye. The microscopic details show also the intermediate 

 condition of the hybrids in the epidermal cells of the outer pitcher surfaces, in the epidermal 

 cells of the conducting surface, in the number of stomata, in the unicellular hairs and hairs 

 on the detentive and inner lid surfaces, in the microscopic structure of the pitcher rim, in the 

 1 liickncss of the leaves, and in other details. Other peculiarities are noted under the caption 

 bisexual hybridity. — John W. Harshberger. 



727. Rutgers, A. A. L. Selectie en uitdunning. [Selection and thinning.] Arch. Rub- 

 bercult, Nederlandsch-Indie 3: 105-118. 1919.— See Bot. Absts. 3, Entry 2051. 



728. Sand, Knud. Experiments on the internal secretion of the sexual glands, especially 

 on experimental hermaphroditism. Jour. Physiol. 53:257-263. Dec. 3, 1919. — Abstract of a 

 monograph by the author, the Danish title as given in the references being, "Experim. 

 Studier over Kons-Karakterer hos Pattedyr. Copenhagen, 191S." — Author has repeated and 

 con firmed Sti.in mm- experiments on guinea-pigs and rats. Castrated males with implanted 

 ovaries became feminized, and castrated females with implanted testes became masculin- 



