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



GENETICS 



G. H. Shull, Editor 

 J. P. Kelly, Assistant Editor 



1419. A., D. The doubling of the stock. Gard. Chron. 66: 157. Sept. 20, 1919.— Author 

 cites references contradicting Mr. Taylor, who states that Lothian growers succeed in 

 obtaining double flowers from single-flowered plants without selection. It seems that seed 

 selection must be made from plants showing tendency to doubling. — A. C. Hildreth. 



1420. Abl [Zuchtinspektor, Halle, Sachsen]. Unfruchtbare Zwillinge beim Rind. [Ster- 

 ile twins in cattle.] Deutsch. Landw. Tierzucht. 22: 34-35. 1918. — Author reviews briefly 

 the theory of Keller and Tandler in regard to the sterility and malformation of the free- 

 martin heifer and describes two extreme examples. — Sewall Wright. 



1421. Allen, Ezra. Studies on cell division in the albino rat (Mus norvegicus, var. alb.). 

 III. Spermatogenesis : the origin of the first spermatocytes and the organization of the chromo- 

 somes, including the accessory. Jour. Morph. 31: 133-185. 58 fig. June, 1918. — A technique 

 which prevents clumping of the chromosomes is described. In the albino rat, the spermato- 

 gonia! number of chromosomes is 37; the accessory divides in the second maturation division. 

 Shapes of the chromosomes in spermatogonia are all curved rods ; in first spermatocytes occur 

 simple and compound rings, crosses, and one rod, the accessory; in the second spermatocytes, 

 curved rods. The constitution of the first spermatocyte chromosomes is typically tetrad, 

 with the four parts so organized that each may retain its individuality. The first spermato- 

 cyte chromosomes pass through clearly marked leptotene, pachytene, and diplotene stages 

 without synizesis. — Bertram G. Smith. 



1422. Alverdes, F. [German rev. of: Boas, J. Zur Beurteilung der Polydaktylie des 

 Pferdes. (Polydactyly in the horse.) Zool. Jahrb. Anat. 4: 49-104. 1917.] Zeitschr. indukt. 

 Abstamm. Vererb. 22: 287-288. May, 1920. 



1423. Alverdes, F. [German rev. of: Lebedinsky, N. G. Darwins geschlechtliche 

 Zuchtwahl und ihre arterhaltende Bedeutung. (Darwin's sexual selection and its significance 

 for the maintenance of species.) Habilitationsvortrag. 31 p. 1918.] Zeitschr. indukt. 

 Abstamm. Vererb. 22: 282-283. May, 1920. 



1424. Alverdes, F. [German rev. of: (1) Naef, A. Die individuelle Entwickelung organ- 

 ischer Formen als Urkunde ihrer Stammesgeschichte. (Kritische Betrachtungen iiber das soge- 

 nannte "biogenetische Grundgesetz.") (The individual development of organic forms as evi- 

 dence of their evolutionary history. — Critical consideration of the so-called "biogenetic law.") 

 77 p. ,4 fig. Jena, 1917. (2) Idem. Idealistiche Morphologie und Phylogenetik. (Zur Meth- 

 odik der systematischen Morphologie.) (Idealistic morphology and phylogeny. — On the method 

 of systematic morphology.) 77 p., 4 fig. Jena, 1919.] Zeitschr. indukt. Abstamm. Vererb. 

 22:279-282. May, 1920. 



1425. Alverdes, F. [German rev. of: Plate, L. Verbungsstudien an Mausen. (In- 

 heritance studies on mice.) Arch. Entwicklungsmech. Organ 44: 291-336. 5 fig. 1918. (See 

 Bot. Absts. 3, Entry 658.)] Zeitschr. indukt. Abstamm. Vererb. 22: 284-285. May, 1920. 



1426. Alverdes, F. [German rev. of: (1) Schaxel, Julius. Grundziige der Theorien- 

 bildung in der Biologic (Principles of theory formation in biology.) G. Fischer: Jena, 1919. 

 (2) Schaxel, Julius. Uber die Darstellung allgemeiner Biologic (On the presentation of gen- 

 eral biology.) Abhandl. Theoret. Biol. 1919.] Zeitschr. indukt. Abstamm. Vererb. 22:276- 

 279. May, 1920. 



