No. 2, SEPTEiMBER, 1921] GENETICS 121 



7C0. ScHWEiSHEiMER, W. Bevolkerungsbiologische Bilanz des Krieges 1914-19. [Popu- 

 lation effects of the war 1914-1919.] Arch. Rass.- u. Gesellschaftsbiol. 13: 176-193. 1920.— 

 This paper reports studies of the effect of the world war on population, considering losses 

 both from deaths and from decrease of births. Tables are given to show the losses under 

 these heads for all of the important countries of Europe. The last part of the paper is devoted 

 to a discussion of the ratio of males to females, showing the decrease in the ratio between 

 1913 and 1919.— L. J. Reed. 



761. SiRKS, M. J. [Dutch rev. of: Schmidt, Johs. Racial investigations. IV. The 

 genetic behavior of a secondary sexual character. Compt. Rend. Trav. Carlsberg Lab. 14*: 

 1-12. PL 1-5 (colored). 1920.] Genetica 3: 77-79. 1921. 



762. Skxjpienski, F.-X. Sur la sexualite chez une espece de MyxomycSte Acrasiee, Dic- 

 tyostelium mucoroides. [Sexuality of a species of Acrasiales, Dictyostelium mucoroides.] 

 Compt. Rend. Acad. Sci. Paris 167: 960-9G2. 1918. — The germination of the spore (in culture) 

 is followed immediately by a motile amoeboid stage. There is no ciliated phase. The myxamoe- 

 bae multiply, the nuclear division being karyokinetic, the chromosome number 4. After 

 a series of divisions, the uninucleate myxamoebae, now relatively large and vacuolate, be- 

 come arranged in pairs and fuse. Fusion of the cytoplasm is followed by that of the nuclei. 

 The zygotes become massed together and sporulation follows. — C. E. Allen. 



763. Slocum, R. R. Methods of pedigree breeding at the government poultry farm. Amer. 

 Poultry Advocate 28: 435-437. 8 fig. 1920. — A brief popular article that contains nothing 

 new. — H. D. Goodale. 



764. Smith, W. G. Special strains of medicinal plants by selection. Pharm. Jour. 104: 

 116-117. 1920. — The present paper is a summary of a semi-popular lecture on breeding medic- 

 inal plants. Principles and methods used in agricultural plant breeding are summarized as 

 follows: (a) Standard species, as of Digitalis and Belladonna, are composed of many varieties 

 which show great diversity when studied intensively; (b) internal qualities are rarely changed 

 by cultivation, fertilization, etc.; (c) improvement within species is obtained by selecting 

 and propagating the best individuals; (d) better results have been obtained by selection of 

 single plants giving rise to pure lines, as for instance in the sugar beet; (e) production of new 

 combinations by hybridization may lead to improvement in any required direction. — To 

 illustrate these principles and methods the author mentions marked improvement and rise 

 in price of French lavender. Strains such as Lavendula verafragrans and L.vera delphiniensis 

 produce the finest oil and thrive at both low and high altitudes. L. spica, a native of lower 

 altitudes, yields very inferior oil, as does the hybrid, L. vera X L. spica. The superiority 

 of English lavender is probably due to long and intensive observation and selection. The 

 standard of yield has been greatly increased where selection of races has been practiced. 

 An effort began in 1904 to improve Hungarian oil of peppermint, resulting in a yield of 62-71 

 per cent of laevocarvone in Hungarian oil of Mentha crispa, as compared with 35-56 per cent 

 in American, 35-56 per cent in German, and 5-10 per cent in Russian. Hungarian oil of M. 

 piperita yields 43-56 per cent free menthol and 35-65 per cent total menthol, as compared with 

 American oil, M. piperita yielding 40-45 per cent free menthol and 60 per cent total menthol. 

 M. piperita has been shown by Camus to be a hybrid between M. viridis and M. aquatica, 

 which thus explains its wide range of variation. The variety "Red mint," cultivated in 

 France and coming more into use, has been found to grow where true peppermint cannot 

 grow, and in the same field for 4 or 5 years, while true peppermint can be grown but 2 years 

 on the same ground. "Red mint" gives a high yield but the oil is of inferior quality. Possi- 

 bility in improvement is indicated by the great variation in M. piperita. — In America, by selec- 

 tion, belladonna, normally yielding 0.23 per cent alkaloid, has been made to yield 0.55 per 

 cent; strains yielding 0.43 per cent have been made to yield 0.72 per cent; and those yielding 

 0.62 per cent have been selected to yield 0.87 per cent. Bj' selection, strains of Datura nor- 

 mally yielding 0.34 and 0.35 per cent of alkaloid have been improved to yield 0.53 and 0.56 

 per cent respectively. [See also Bot. Absts. 6, Entry 825.] — Francena R. Meyer. 



