June, 1920] GENETICS ML".) 



parts derived from the other would necessarily lead to complete reversion of a character. — 

 Hybridized gemmules derived from both parent hybrids would simply reproduce the i riginal 

 hybrid form." "Act of crossing tends to bring back long lost characters aol proper to 'lie 

 immediate parent form." He observed somatic segregation in I \ and doubted whether the 

 length of time a character had been inherited had any influence on its fixedness. He also 

 observed sex-linked inheritance. — Merle C. Coulter. 



2186. Roberts, Herbert F. The contribution of Carl Friedrich von Gartner to the his- 

 tory of plant hybridization. Amer. Nat. 53: 431-445. Sept.-Oct., 1919. — Selected quotations 

 and brief comments. In 183G Gartner received a prize for the first satisfactory demonstra- 

 tion of fact of hybridization in plants; 1849, published results of 25 years' work, involving 

 10,000 separate experiments in crossing. Classed hybrids: (1) intermediate types, — occasional 

 cases where one parent contributed more strongly being due to "slight overbalance of one or 

 other fertilization materials;" (2) commingled types, each parent contributing certain char- 

 acters; (3) decided types, one parent being prepotent. Visualized determination of hybrid 

 characters as due, "not to mass and relationship of germinal materials," but to "vital modi- 

 fication of formative force." Essential nature of a species consists in definite relation of its 

 sexual forces to other species (crossability), not necessarily in morphological features. No 

 thought of unit characters; hybrid types "must be compared in their totality." Variation 

 in F 2 described but not explained. Identical results of reciprocal crosses emphasized. 

 Decided against xenia in corn, unfortunately using pericarp color, but got positive results 

 with peas (yellow and green seeds). Emphasized necessity of pure parent types, and repeti- 

 tion of experiments using different individuals. Hybrid vigor seen clearly, and its agricul- 

 tural possibilities considered. — Merle C. Coulter. 



2187. Salmon, C. E. Papaver Rhaeas, P. dubium and the hybrid between them. New 

 Phytol. 18: 111-117. 7 fig. Mar -April, 1919. — Author presents evidence indicating that 

 wild plants at first taken to represent a variety of Papaver dubium are hybrids between P. 

 dubium and P. Rhaeas. Significant characters of parents and hybrids are listed and conclu- 

 sion is drawn that some characters of the hybrids belonged to one parent, some to the other, 

 whilst a few were perfectly intermediate. The hybrids were completely sterile. — T. II. 

 Goodspeed. 



2188. Salmon, C. E. A hybrid Stachys. Jour. Linnean Soc. London (Bot.) 44: 357- 

 362. 1 fig. May 16, 1919. — Paper is of taxonomic interest chiefly. S. germanica is 75 cm. 

 high; S. alpina is 60 cm.; S. digenea, a natural hybrid between the two, is 107 cm. — Merle 

 C. Coulter. 



2189. Salmon, E. S. On forms of the hop (Humulus lupulus L.) resistant to mildew 

 (Sphaerotheca humuli (DC) Burr.); II. Jour. Genetics 8: 83-91. Apr., 1919. — Continua- 

 tion of earlier experiments (Jour. Agric. Sci. 8: 455, 1917) which indicated that certain indi- 

 vidual seedlings of wild hop, obtained from Vittorio, Italy, and female variety with yellow 

 leaves known as "golden hop" were both resistant to attacks of Hop-mildew (Sphaerotheca 

 humuli (DC.) Burr). Inoculation experiments with these two groups of "immune plants" 

 continued with the result that seedlings of first group when grown in greenhouse were immune 

 as regards leaf and stem during two consecutive seasons although when planted out in the 

 hop garden susceptibility appeared late in the growing season in the case of leaf and "hop." 

 Greenhouse plants may' show local susceptibility without the general immunity being lost. 

 In second group the yellow-leaved female variety is found to be immune while corresponding 

 male variety is susceptible. — T. H. Goodspeed. 



2190. Schmidt, Johannes. Der Zeugungswert des Individuums beurteilt nach dem Ver- 

 fahren kreuzweiser Paarung. [Individual potency, based on experiences in cross-matings.] 

 8 vo., 40 p. Gustav Fischer: Jena, Germany. 1919. — Translation from a Danish manuscript, 

 dealing with inheritance of quantitative characters. Knowledge of individual potency often 

 has great theoretical or practical significance, for instance in the selection of individuals for 



