158 GENETICS [BoT. Absts., Vol. X, 



ing for differential viability. It is suggested that the terms tetraploid and triploid might well 

 be used, at least in the strict sense, only for plants which have in each set respectivelj^ 3 or 4 

 strictly homologous chromosomes. — In chromosomal duplication no new genes are added. The 

 striking effects produced are due to the disturbance of the normal balance between all the 

 genes of the diploid group of chromosomes. Thus triploid plants, where there is no special 

 disturbance of this balance, are as yet only to be distinguished from normals by their pollen, 

 and the same is the case with some tetraploids. — For the formation of new species from tetra- 

 ploid plants it seems requisite that the 4 chromosomes of a set should cease to assort at random, 

 and should pair only in separate sets of 2. Such double diploid plants would be distinguished 

 by having duplicate genes, giving a 15:1 ratio v/hen doubly heterozygous. The same would 

 apply to plants with only 1 set of 4 chromosomes, and the rest in pairs. — John Belling. 



1039. Blaringhbm, L. Recherches sur les hybrides du lin (Linum usitatissimum L.) 

 [Studies on the hybrids of flax.] Compt. Rend. Acad. Sci. 175: 329-331. 1921.— Flax culti- 

 vated for seed is more homogeneous than flax cultivated for fiber. Crossing with white-seeded 

 flax was used to study genetic constitution of the flax of Maroc, the crossing, however, being 

 difficult and resulting in few plants. Brown color and ciliated walls of Maroc proved domi- 

 nant over white color and naked walls in fruit of flax with white seeds. Maroc shows 2 lines, 

 one acting as a carrier of simple Mendelian characters, the other of complex characters. 

 Separation of lines by testing with known combination is the basis of technique in flax selection. 

 — Helen D.Hill . 



1040. Blaringhbm, L. Variation de la forme des feuilles, correlatives de la sexualite, 

 observees sur des genevriers (Juniperus chinensis L., J. phoenicia L.). [Variation of the form 

 of the leaves correlative with sexuality observed in the junipers.] Compt. Rend. Soc. Biol. 84: 

 500-502. 1921. — The author examined a male plant of /. chinensis and a female plant of J. 

 'Phoenicia for correlation between sporophylls and vegetative leaves. Below were branches 

 with awl-shaped (juvenile) leaves and without cones; above were branches with scale leaves 

 accompanied by cones. A few cases of cones among needle-shaped leaves remind the author 

 of rare cases of paedogenesis, as in Axoloil. — /. P. Kelly. 



1041. Claussen, p. [German Rev. of: Blakeslee, A. F. Lindner's roll-tube method 

 of separation cultures. Phytopathology 5: GS-69. 1 pi. 1915.] Zeitschr. Bot. 13: 597-598. 

 1921. 



1042. Collins, J. L. Reversion in composites. Jour. Heredity 12: 129-133. Fig. 16-19. 

 1921. — The paper describes and figures a teratological form of Crepis capillaris resulting 

 from a cross between Dutch and Swedish strains. Normally the plant has a perfectly smooth 

 and naked receptacle, but on one plant appeared foliaceous palea-like bracts subtending the 

 achenes of every head; this is considered a possible reversion to a pre-composite state. The 

 composite capitulum maj" be developed through the shortening of a spike, or from an umbel in 

 which the pedicels have disappeared. In the former case, according to James Small, the 

 receptacle might be expected to be conical instead of flat, and in the latter the plant would 

 have lost the bracts subtending the inner pedicels in the pre-composite stage. The author 

 holds that the proliferated Crepis head, and also a somewhat analogous one of Hypochaeris, 

 which he figures, support the umbellate-origin hypothesis. It is further suggested that in the 

 past the genetic factors involved in producing such structures as are described may have 

 become separated and are rarely brought together in crossing. The case is then to be con- 

 sidered as resembling that of the white sweet-peas which on crossing give a purple, or the 

 mutant types of Drosophila which when united produce flies of the wild, or typical, form. — 

 T.D.A. Cockerell. 



1043. Coulter, M. C. Mutation. [Rev. of: (1) Baur, Erwin. Mutationen von Antir- 

 rhinum majus. (Mutations of Antirrhinum majus.) Zeitschr. Indukt. Abstamm.-u. Vererb. 

 19:177-193. lOfig. 191S (seeBot. Absts. 2, Entry 1198;3, Entry2183). (2) Zeleny, Charles. 

 The direction and frequency of mutation in a series of multiple allelomorphs. Anat. Rec. 20: 



