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



1484. Demoll, R. Zur Frage nach der Vererbung vom Soma erworbener Eigenschaften. 

 [On the question of the inheritance of acquired characters.] Arch. Entwicklungsmech. Organ. 

 46:4-11. 3 fig. 1920. 



1485. Detjen, L. R. A mutating blackberry — dewberry hybrid. Jour. Heredity 11: 92- 

 94. 4 fig. Feb., 1920. 



1486. Detlefsen, J. A., and W. W. Yapp. The inheritance of congenital cataract in cat- 

 tle. Amer. Nat. 54: 277-280. May- June, 1920.— On mating the F x son of Holstein-Friesian 

 bull 62924 to the Fi daughters of this bull 8 F 2 offspring (2 9 and 6c?) with well-defined con- 

 genital cataracts of the stellate type to 55 F 2 normal offspring were produced. Ninety-three 

 normal F! offspring of 62924 were produced. Pedigree studies of bull 62924 reveal no ances- 

 tors which had cataracts. Assuming the bull 62924 heterozygous the F 2 expectation is 55.125 

 normal + 7.875 cataractous. 62924 mated to his own daughters produced 7 offspring, 3 (lc? 

 4- 2 9 ) of which were cataractous. It is concluded that congenital cataract in cattle is a 

 simple recessive Mendelian character. — John W. Goxcen. 



1487. De Vries, Hugo. Oenothera Lamarckiana erythrina, eine neue Halbmutante. 

 [Oenothera Lamarckiana erythrina, a new half-mutant.] Zeitschr. indukt. Abstamm. Vererb. 

 21:91-118. 1919. 



1488. Don caster, L. The tortoiseshell tomcat. A suggestion. Jour. Genetics 9: 335- 

 338. Mar., 1920. — Author criticizes Little's hypothesis of mosaic character of tortoiseshell 

 tomcat and on basis of work of Chapin, Lillie, and Magnusson on free-martin and of Cut- 

 ler and Doncaster on histology of testis of sterile tortoiseshell tomcat, suggests that latter 

 be a masculized female. — P. W. Whiting. 



1489. Doncaster, L., and H. G. Cannon. On the spermatogenesis of the louse (Pedicu- 

 lus corporis and P. capitis), with some observations on the maturation of the egg. Quart. Jour. 

 Microsc. Sci. 64: 303-328. 1 pi., 1 fig. Mar., 1920. — P. corporis has 12 chromosomes in somatic 

 cells of both sexes. In the testis certain large cells, supposed to be follicular, also have 12. 

 Other cells of testis, believed to be spermatogonia, have 6, apparently double, chromosomes. 

 Spermatocytes, also with 6 chromosomes, pass through growth period followed by a very asym- 

 metrical division, giving one large cell which develops into a spermatid and one small "polar 

 cell" which degenerates. A conspicuous mitochondrial body remains in the large cell. No 

 second spermatocyte division occurs. Centrosomes of spermatids are double and there are 

 two axial filaments. No oogonial or oocyte divisions were found. Author did not observe 

 unisexual broods or sex-ratio disturbances described by Hindle. Spermatogenesis of P. 

 capitis apparently agrees with that of P. corporis. — C. W. Metz. 



1490. Duerden, J. E. Methods of degeneration in the ostrich. Jour. Genetics 9: 131-193. 

 PL 5-6, 8 fig. Jan., 1920. — Author describes type of degenerative changes observed in coverts, 

 wing quills, down feathering, wing digits and toes, and regards these as suggestive of the man- 

 ner in which degeneration proceeds, and as favorable data for throwing light on the nature 

 of variation and method of evolution generally. — -In his discussion of relation of the degenera- 

 tive changes to adaptation, author concludes that, compared with other factors, such losses 

 have little or no bearing upon the welfare of the ostrich; and hence, that natural selection has 

 been inoperative in directing their course. "Natural selection may wipe out the race, but 

 cannot guide its evolution." — Referring to ontogenetic and phylogenetic degeneration, 

 author believes process of degeneration is in no way affected during the life of the individual, 

 but only with the formation of the zygote; in plumes, scales and claws of embryos and chicks 

 the degenerative changes are found expressed just as in the adult. "Degeneration may be 

 defined as the somatic expression of a phylogenetic degradation and loss of genetic factors." 

 — As to cause of degeneration, author acknowledges our ignorance on this point but believes 

 they are certainly intrinsic as opposed to environmental. "The influence is so slowly acting 

 . . . as to call for an aloofness, an independence, of external vicissitudes. Only something 



