No. 1, July, 1920] GENETICS 87 



more reliable and shows lti.i per cent crossovers in b total of 1449. The results from P| 

 mated inter se giving a total of 708 agree tolerably well with this. — ■/. .1. Detlefsen and E. 

 Roberts. 



."(;.".. |)i;n.: , 3BN, J. A., AND YV. W. Y \i'i*. On the inheritance of congenital cataract in 

 dairy cattle. Ana 1 . Rec. 17:339. Jan. '20, 1920. [Author's abstract of paper read before 

 American Society of Zoologists, St. Louis, December 30, 1919.] — A pure-bred Bolstein-Friesian 

 bull, R. T. H., was mated to unrelated cows, and produced ( x\ normal Fi offspring. His 

 normal I\ son, 1. V. II., was mated to 32 normal I\ sisters and half-sisters, giving 03 off- 

 spring, of which 8 (0 bulls 4- 2 heifers) showed well-defined congenital cataract. The sire, 

 E. T. II., was also mated to Fi daughters, producing 7 offspring, of which 3 (1 bull 4- 2 

 heifers) wme blind. If congenital cataract is a simple recessive character, then the sire and 

 son should produce a population of which 12.5 per cent are blind. The total results, 70 off- 

 spring, of which 59 were normal and 11 were blind, agree tolerably well with the calcula 

 expectal ion, 01.25 normal plus 8.75 blind. — J. A. Dctlefsen and W. W. Yapp. 



500. Dorsey, M. J. Bud variation as a practical asset in horticulture. Minnesota Hortic. 

 46: 304-311. 2 fig. 1918. — Relation between bud variations and improvement of horticultural 

 varieties. Cites monographs of New York (Geneva) Station which show that 5 of 2004 varie- 

 ties (apple, cherry, grape and plum) arose by bud variations. Gives instance of supposed 

 bud sport in Duchess apple, which reproduced itself when top-worked. Shape of apple was 

 unchanged but fruit was of darker red color. Selection of scions from best plants is sound 

 practice. — H. K. Hayes. 



507. Dorsey, M. J. A study of sterility in the plum. Genetics 4 : 417-488. 5 pi. Sept., 

 1919. — Sterility is of the type of self- and cross-incompatibility and of embryo abortion. 

 Normal pollen development typical; many aborted grains found in all varieties investigated 

 and in some supposedly pure species but pollen abortion not a cause of sterility except in 

 rare instances where suppression is complete. Percentage of aborted pollen higher in hybrids 

 than in species supposed to be pure. Pistils drop in three separate and distinct waves: imme- 

 diately after bloom, pistils aborted; 2 to 4 weeks after bloom, pistils not fertilized; 2 weeks 

 later "June drop," pistils fertilized but embryo development stopped. Pollen abortion 

 considered to be due to haploid factor combinations not suitable for development. — D. F. 

 Jones. 



508. Duerden, J. E. The germ plasm of the ostrich. Amer. Nat. 53: 312-337. 3 fig. 

 July-Aug., 1919. — Germ plasm (or determiners) of the ostrich is considered from two oppos- 

 ing view points, one holding it to be stable, the other labile. In support of the first view, it is 

 stated that each bird produces over 200 feathers annually, which are minutely examined. 

 In the 50 years of methodical ostrich farming " .... a feather variation, germinal in its 

 origin, such as could be regarded as of the nature of a sport or mutation" has not appeared. 

 On the other hand, there is considerable variation in the number of rcmiges, wing coverts, 

 toe nails and the scutes of the feet, thus affording evidence of instability of the germ plasm. 

 — H. D. Goodale. 



509. Dunn, L. C. Anomalous ratios in a family of yellow mice suggesting linkage between 

 the genes for yellow and for black. Amer. Nat. 53: 558-500. Nov.-Dec, 191S. — A family of 

 yellow mice heterozygous for factors Y for yellow, and B for black, descended from a cross 

 of black and tan, YyBB, and brown yybb, has given an excess of brown and a deficiency of black 

 young among the non-yellow animals produced. It seems that linkage between factors for 



Y and B is involved or that discrepancies are due merely to chance. Further data to 

 decide this point are hoped for. — C. C. Little. 



570. Durken, Bernhard. Einfiihrung in die Experimentalzoologie. [Introduction to 

 experimental zoology.] x + 446 p., 224 fig- Julius Springer: Berlin. 1919. 



