ANIMAL PRODUCTION. 369 



The structure of reproductive organs of domesticated animals, R. Schmai-tz 

 (Die Struktur der Geschlechtsorgane der Haussuugetiere. Berlin, 1911, pp. 

 XII+3SS, figs. 168; abs. w Jour. Roy. Micros. Soc. [London], 1911, No. 6, p. 

 tJfS). — A monograph on the generative organs of the horse, ox, sheep, pig, dog, 

 and cat. 



The function of the accessory reproductive glands in male mammals, E. 

 IwANov {Arch. Mikros. Anat., 77 (1911), No. 2, II, pp. 240-2JfS; abs. in Jour. 

 Roy. Micros. Soc. [London], 1912, No. 2, p. 167). — The author concludes that 

 the main function of the accessory male reproductive glands is to supply a 

 diluting medium for the spermatozoa. The secretion of the prostate also con- 

 tains elements which apparently contribute to fermentative processes, and 

 vrhich seem to inci-ease the locomotor energy of the spermatozoa and to shorten 

 their length of life. 



The origin of sexual differences, P. Kammeeer (Fortschr. Naturic. Forsch.,' 

 5 (1912), pp. l-2JfO). — A systematic summary and critical discussion of the 

 nature and causes of sex, effect of castration, and related topics, if 



A bibliography of about 700 references is appended. 



Becent work on the determination of sex, L, Doncastee (Ann~ Rpt. Smithsn.' 

 Inst. 1910, pp. Jf73-^S5). — A reprint, with additions, of an article noted from 

 another source (E. S. R., 22, p. 273). 



Historical-critical studies on hair and hair colors in domesticated animals, 

 with special reference to abnormal whitening, H. Wiegmann (Historisch- 

 kritische Stiidien iiher Ilaar- und Hautfarben bci Haustieren mit besonderer 

 Beriicksiclitigung des Albinismus und LeUfCismivs. Inaug. Diss., Univ. Bern,' 

 1910, pp. ^8). — A review of the literature on the causes of localization of pig- 

 ment in horses, cattle, sheep, and swine. 



Concerning an important kind of hair and the hair coat system of mam- 

 mals, K. ToLDT, Jr. (Ann. K. K. Naturhist. Ilofmus. [Vienna], 2^ (1910), No. 

 1-2, pp. 195-268, pis. 4, fig. 1). — The morphology, physiology, and distribution 

 of different kinds of hair in mammals are treated in detail. A bibliography 

 is appended. 



Comparative anatomy of supernumerary digits in certain ungulates as 

 evidence of the interrelationship existing between the various species, J. 

 Shake-Jones (Vet. Jour., 67 (1911), Nos. 429, pp. l.',5-157; 432, pp. 344-355, 

 figs. 10). — A comparative study of abnormal digits in the horse, ox, and pig. 

 The principal structures noted in detail are the bones, tendons, and ligaments. 



The continuous origin of certain unit characters as observed by a paleon- 

 tologist, H. F. OsBOEN (Amer. Nat., 46 (1912), Nos. 544, pp. 185-206; 545, pp. 

 249-278, figs. 8). — The author's studies of the skull and horns of Titanotheres, 

 the horns of cattle, the cranium of man, and the skull and teeth of horses 

 indicate that discontinuity in heredity affords no evidence whatever of discon- 

 tinuity of origin, and that new characters arise by excessively fine gradations 

 which appear to be continuous. If discontinuities or steps exist they are so 

 minute in these characters as to be indistinguishable from those fluctuations 

 around a mean which seem to accompany every stage in the evolution and 

 ontogeny of unit characters. 



" Because the grosser form of Larnarckian interpretation of transmission of 

 acquired characters has apparently been disproved, we must not exclude the 

 possibility of the discovery of finer, more subtle relations between the germ 

 plasm and the soma, as well as the external environment." 



The inconstancy of unit characters, W. E. Castle (Amer. Nat., 46 (1912), No. 

 546, pp. 352-362). — In opposition to the views of the genotype and pure line 

 advocates, the author finds that by constant selection in one direction a char- 

 acter may be modified gradually, and cites examples of his own experience in 



