No. 4, January, 1921] GENETICS 261 



working locally for production of uniform stands through selection of proper plants and 

 dissemination of cuttings <>f them. Author lias started such selection in above-mentioned 

 region before war. [From anonymous review in Zeitschr. Pfianzenzticht. 7: 220. June, 1020.] 

 — /. P. Kelly. 



1787. Waldron, J. W., A. Gabtlbt, C. R. Bembnwat, J. X. 8. Williams, C. P. Wilcox, 

 T. II. Petrie, and 11. P. Agee. Report of the committee in charge of the Experiment Station. 

 Rept. Exp. Sta. Hawaiian Sugar Planters Assoc. 1919. 49 p. 1920. — See Bot. Absts. 6, 

 Entry 901. 



1788. Wince, 0. Uber die Vererbung der Haarfarbe der Pferde. [Heredity of hair color 

 in the horse.] Zeitschr. indukt. Abstamm. Vererb. 24: 1-32. Aug., 1920. 



1789. Wodsedalek, J. E. Studies on the cells of cattle with special reference to sperma- 

 togenesis, oogonia, and sex-determination. Biol. Bull. 38: 290-316. 5 pi. May, 1920. — 

 Material for the study of the germ cells of males were obtained from the testes of seven adult 

 bulls, one five-month fetus, and six smaller fetuses; for the cells of females, from the ovaries 

 of four heifers and four adult cows. Somatic cells were studied in slides from various parts 

 of a number of embryos and small fetuses of each sex. — In the male, 37 chromosomes (36 

 ordinary and 1 accessory) appear in spermatogonial divisions. The accessory is heart-shaped 

 and therefore easily identified in this and succeeding divisions. It is identified with the 

 large nucleolus of resting stages. In the primary spermatocytes, 18 bivalent chromosomes 

 and 1 accessory appear in metaphase. The accessory passes undivided to one pole; so that 

 half of the secondary spermatocytes receive 19, and half, 18 single chromosomes. A second 

 doubling of chromosomes occurs; so that the equatorial plate of the secondary spermatocytes 

 reveals 9 and 10 chromosomes (9 plus the accessory), respectively. The accessory, when 

 present, and each of the doubled chromosomes divide. But the division is not reductional in 

 nature; hence half of the spermatids really receive the equivalent of 18 single chromo- 

 somes, and half receive 19. Occasionally the 18 (or 19) chromosomes can be distinguished 

 after division, but usually the chromosomes pass to the resting stage before complete sepa- 

 ration occurs. Measurements of six hundred heads show that there are two classes of sper- 

 matozoa. Those of the larger type presumably contain the sex-chromosome. — The oogonia 

 resemble the last spermatogonial cells closely in appearance although they are larger and 

 possess two distinct accessory chromosomes. It is inferred that the reduced number of 

 chromosomes in each mature ovum is 19, inasmuch as 38 appear in oogonial divisions. Male 

 somatic cells contain 37 chromosomes, and female somatic cells, 38 chromosomes. The 

 sex chromosomes in somatic cells — one in the male, two in the female — were as distinguishable 

 as in the germ cells. — M. F. Guyer. 



1790. Wohanka and Company. 28. Jahresbericht der Rubensamenziichtungen von 

 Wohanka & Comp. [28th annual repor.t of the beet breeding of Wohanka & Co.] 95 p., 5 fig. 

 Wohanka & Co. : Prag, 1918.— See Bot. Absts. 6, Entry 1624. 



1791. Zade. Die Versuche uber Klee- und Graserzuchtungen des landwirtschaftlichen 

 Instituts Jena. [Experiments in clover and grass breeding of the Jena Agricultural Institute.] 



ahrb. Deutsch. Landwirtsch. Ges. 1918: 139-150. 1918.— See Bot. Absts. 6, Entry 1625. 



1792. Ziegler, H. E. Zuchtwahlversuche an Ratten. [Selection experiments on rats.] 

 Festschr. z. Feier. 100-jahr. Best. Kgl. Wiirtt. Landw. Hochschule Hohenheim. 1918: 385- 

 399. 1918.— The author was able to modify the amount of white in the coat of Irish rats by 

 selection. He explains his results by the multiple factor hypothesis. — Seiarfl Wright. 



1793. Zweig, Ltjdwig. Uber einen Fall von Epidermolysis bullosa hereditaria. [On a 

 case of epidermolysis bullosa hereditaria.] Arch. Dermatologie u. Syphilus 120: 1-6. 19 — . 



