No. 1, February, 1921] GENETICS 33 



and demand for particular types of cotton, to work of breeder and grower; impurity of com- 

 mercial varieties in Egypt due to crossing and seed mixture; and relation of yield and quality 

 to physical environment. He outlines a program of economic, botanical, and agricultural 

 investigations looking to improvement of crop with especial emphasis upon breeding and 

 increase of pure lines to replace present mixed commercial stocks. He discusses complica- 

 tions caused by uncontrolled introduction of new varieties. — T. H. Kearney. 



218. L^CAiLLON, A. Sur la reproduction et le developpement des bivoltins accidentels et 

 de la premiere generation qui en derive, chez le Bombyx du M(irier. [On the production and 

 development of accidental bivoltins and the first generation derived from them in the silkworm 

 (Bombyx mori). Compt. Rend. Acad. Sci. 168: 366-368. 1919. 



219. LiPPiNCOTT, W. A. Pedigreeing poultry. Kansas Agric. Exp. Sta. Giro. 67. 16 p., 

 10 fig. 1918.— Methods of pedigreeing poultry, including methods of marking breeders and 

 offspring, trapnests, methods of pedigree hatching, chick and mating indexes, marking of 

 eggs, flock breeding records, pedigree blanks and egg records are given. — H. D. Goodale. 



220. Little, C. C. Alternative explanations for exceptional color classes in doves and 

 canaries. Amer. Nat. 54: 162-175. Mar.-Apr., 1920. — The author reviews the explanation 

 based on partial sex-linkage and non-disjunction previously offered to account for the appear- 

 ance of exceptional color classes in doves and canaries, and concludes that neither is adequate. 

 He then advances the theory that these occasional cases may be the results of mutative 

 changes of the recessive factors to their dominant allelomorphs. His view has no more 

 proof in existing data than the others, but has the advantage of avoiding the immediate 

 expectation of color classes which have not been reported. [His suggestion, however, that 

 female doves and canaries may be homozygous for dominant sex-linked factors is contrary 

 to all present experience.] — L. J. Cole. 



221. Lloyd-Joxes, O., and F. A. Hays. The influence of excessive sexual activity of 

 male rabbits. I. On the properties of the seminal discharge. Jour. Exp. Zool. 25:463-497. 

 1918. — The plan of the experiment as stated by the authors was "to have the male accom- 

 plish, in as rapid succession as possible, a certain number of preliminary 'services' and then 

 to mate him once to the breeding female from which the litter was desired. The 'end serv- 

 ices' from which litters were secured for the progeny studies were the fifth, tenth, fifteenth 

 and twentieth, and about an equal number of first-service litters M'ere obtained as controls. 

 When semen studies were made, however, it was aimed to recover specimens from the first 

 and from every fifth service thereafter; thus, in a series of twenty services, five specimens of 

 semen would ideally be recovered for study. This ideal set of specimens from a twenty- 

 service series was seldom obtained, however." — It was' shown that excessive sexual service 

 causes decrease in amount of ejaculated semen, decrease in number of sperm cells per cubic 

 millimeter, decrease in the proportion of sperm that show progressive motion, decrease in their 

 duration of motion, decrease in percentage of fertile matings, and decrease in number of 

 young per litter. — H. L. Ibsen. 



222. LiTNDBORG, H. Arv och miljo. Befolkningspolitiska synpunkter. [Inheritance and 

 environment. Race-political views.] Det nya Sverige [Stockholm], 14: 3-12. 1920. — Author 

 holds that great crossing of races degenerates constitution and increases degradation. Cross- 

 ing of races takes place in a much greater degree among the lower and poorer part of the 

 population than among the middle classes. Author has proved by his own investigations 

 that the lowest classes — those which are in social respect the most degenerated of the popu- 

 lation — consist to a greater extent of individuals with other race-qualities, such as darker 

 hair and eyes, than the great bulk of the population. The middle class has a more homo- 

 geneous composition than the poorer ones. The biological sciences are nowadays promoting 

 a new social evolution, by which the most important matters are life values and not wealth 

 or other material advantages. Great and richly equipped eugenical scientific institutions 

 must be established in all civilized countries. — K. V. Ossian Dahlgren. 



BOTANICAX ABSTRACTS, VOL. VII, NO. 1 



