No. 3, April, 1921] GENETICS 243 



16Go. VuiLLEMiN, P. L'amphigonelle et la phylogenie des amentales. [The "amphigonelle" 

 and the phylogeny of the Amentales.] Ann. Sci. Nat. Bot. X, 1: 139-200. 1919.— See Bot. 

 Absts. 7, Entry 336. 



1666. Webster, A. D. The systematic afforestation of Great Britain. Jour. Roy. Hort. 

 See. 45:278-288. 1919.. 



1667. Zeller, S. M. Humidity in relation to moisture imbibition by wood and to spore 

 germination on wood. Ann. Missouri Bot. Gard. 7: 51-74. 1 pi., 5 Jig. 1920. — See Bot. Absts. 

 7, Entry 400. 



GENETICS 



George H. Shull, Editor 

 James P. Kelly, Assistant Editor 



1668. Agar, W. E. The genetics of a Daphnia hybrid during parthenogenesis. Jour. 

 Genetics 10: 303-330. 3 fig. Dec, 1920.— Attempts to get intergeneric crosses between Daph- 

 nia and Siinocephalus failed. Reciprocal hybrids were obtained between Daphnia obtusa and 

 D. pulex, though the percentage of successful matings between parent species was low. Few 

 of the fertilized eggs of hj^brid or straight matings hatched. From 21 fertile ephippia from 

 cross-matings hatched, only three young were produced, two of which gave offspring. One 

 was lost after three generations, others were carried ten parthenogenetic generations. Hy- 

 brid clones were characterized by (1) e.xcessive production of sexual eggs, (2) excessive pro- 

 duction of males, (3) complete sterility of males, (4) incomplete fertility of parthenogenetic 

 eggs (approximately half failed to develop), and (5) probably normal fertility of sexual eggs 

 (wRen fertilized by males from parent clones). — 'As a character for study of inheritance author 

 used ratio between body length and length of second abdominal process, and ratio between 

 lengths of second and third abdominal processes. The former (mean) ratio for males of 

 D. obtusa of the parent clone was 30.8, for D. pulex 6.2, and for the hybrid clone 10.1. The 

 latter ratio for the females of D. obtusa was 2.17, for D. pulex 2.89, and for the hybrid clone 

 1.97. The distribution curves of the hybrids while slightly skew (due to environmental fac- 

 tors) were steep curves and showed no tendency toward bi- or multimodality. "There is no 

 evidence of progressive increase in diversity in successive generations, whether measured 

 by the standard deviation or by the extreme range of variation." The conclusion is "that 

 during the parthenogenetic reproduction of these forms, which is not accompanied by reduc- 

 tion of chromosomes, Mendelian segregation does not take place, nor does genetic diversity 

 between parent and offspring normally arise." — A. M. Banta. 



1669. Anoxymous. A common misconception concerning human heredity. Jour. Hered- 

 ity 10: 275. 1919. ^Environment produces greater modifications in plant life than in animal, 

 and far greater on simpler animal tissue than on the more complex.— J. H. Beaumont. 



1670. Anonymous. Disease proof potatoes. Florists' Exchange 50: 1067. Nov. 20, 1920. 

 —Certain potato varieties, including Irish Cobbler, are immune to wart disease. No variety, 

 however, has appeared that is resistant to late blight {Phytophthora) , although some varie- 

 ties are more resistant than others. — -Richard Wellington. 



1671. Anonymous. A factor influencing the sex-ratio. Jour. Heredity 10: 256. June, 

 1919. — 'Author shows from the results of Helen Dean King, Morgan, Riddle, Moenkhaus, 

 and Papanicolau that the female has more influence in determining the sex-ratio, though 

 a knowledge of the interactions of the germ-cells must be gained before the problem can be 

 solved. — J. H. Beaumont. 



1672. Anonymous. Heredity of cancer. Jour. Heredity 10:89. 1919.^Pointing out 

 racial susceptibility and some family susceptibilities to cancer as argument for placing cancer 

 on a heredity basis. — ■/. H. Beaumont. 



