64 GENETICS [Bot. Absts., Vol. V, 



dens than for those at exhibitions. The custom of bracketing the breeder's name after the 

 name of the variety is spreading among Iris specialists. Parentage should be put on record. — 

 John Belling. 



469. Sumner, F. B. Continuous and discontinuous variations and their inheritance in 

 Peromyscus. Amer. Nat. 52: 177-208. 12 fig. April-May, 1918. — Discusses in this first paper 

 structural and pigmental differences in the western deer mouse, Peromyscus maniculatus 

 (Wagner) based on collections from four climatically different localities in California, — 

 Eureka, Berkeley, LaJolla, and Victorville. Humidity and rainfall are in a descending, and 

 mean annual temperature in an ascending, order for localities as given. Considers hair color 

 including microscopical structure, skin color, length of body, tail, foot, and ear, and number 

 of tail vertebrae, illustrating by histograms and ordinary graphs. — Finds for pigmentation, 

 intensive and extensive, series is Eureka>Berkeley>LaJolla> Victorville. For tail length 

 Eureka>LaJolla>Berkeley and Victorville. For number of caudal vertebrae, Eureka> 

 LaJolla>Victorville. For foot length, Eureka>LaJolla, Berkeley and Victorville. Ear 

 length LaJolla>Eureka and Victorville>Berkeley. General conclusions reserved for final 

 paper. — L. B. Walton. 



470. Tammes, T. Die Flachsbliite. [The flower of flax.] Recueil Trav. Bot. Neerland. 

 15: 185-227. 2ft fig. 1918— See Bot. Absts. 5, Entry 310. 



471. Taylor, H. V. The popularity and deterioration of potatoes. Card. Chron. 67: 108. 

 Feb. 28, 1920. — New potato varieties are usually lower in quality than old standard varieties 

 but at the same time are more resistant to diseases and adverse conditions. With cultivation 

 and propagation the qualities improve, but vigor and disease resistance decreases. These 

 simultaneous changes are held responsible for the appearance of six varieties which have 

 attained popularity and each after ten to fifteen years have been succeeded in turn by another 

 new variety. — J. L. Collins. 



472. Thelltjng, A. Neure Wege and Ziele der botanischen Systematik erlautert am Bei- 

 spiele unserer Getreidearten. [New methods and purposes of botanical taxonomy illustrated 

 by examples of our cereal species.] Naturw. Wochenschr. 17: 449^458. 465-474. S fig. 191S. 



473. Thellung, A. tiber geschlechtsbegrenzte Speziesmerkmale (zu dem Aufsatz von 

 Brehm). [On sex-limited species characters (in response to von Brehm).] Naturw. Wochen- 

 schr. 18: 144. 1919. 



474. Thomas, Roger. The improvement of "Tinnevellies" cotton. Agric. Jour. India 

 14: 315-330. 1919. 



475. Turesson, G6te. The cause of plagiotropy in maritime shore plants. Contributions 

 from the plant ecology station, Hallands Vadero, No. 1. Lunds TJniversitets Arsskrift. N. F. 

 16 2 : 1-33. 15 tables, 4 fig-, # pi- 1919. — The prostrate form of some shore plants is demon- 

 strated to depend upon geotropism induced by brilliant sunlight ("photocliny")- In obscure 

 light the geonegative reaction becomes predominant. — From one hereditary point of view 

 it is interesting to find that the prostrate vegetation can be made up of two genetically 

 different elements, viz., modificatory prostrate forms, and hereditary prostrate variations. 

 Both forms are sometimes found within the same systematic species. Alriplex latifolium, 

 A. rat idum and Chenopodium album have each a forma "prostratum," which is constantly 

 plagiotropic; the main species are only plagiotropic in intense light and erect in ordinary light. 

 When growing together on exposed beach it may be difficult to separate the two types, and 

 cultivating of them becomes necessary. By self-fertilization the prostratum form of both the 

 A triplex-species is found to breed true to plagiotropy. — "The hereditary prostrate variations 

 differ physiologically from the prostrate modifications in being more sensitive to light; they 

 respond to conditions of illumination which leave the latter unaffected and in a vertical posi- 

 tion." Author supposes that the prostrate races have come into existence by dropping out 

 of "heighf-determining factors. — A". V. Ossian Dahlgren. 



