132 GENETICS [Bot. Absts., Vol. IV, 



the third and fourth generation. All of the seedlings obtained from the male plants were pre- 

 vailingly male, only a few developing a few female flowers. The same results were obtained 

 in the second generation in the male plants. Observations on this species show plants which 

 produce only female flowers, others which produce only male flowers, and others which show 

 gradations between pure femaleness and pure maleness. A rather extensive review of the lit- 

 erature on inheritance in sex, especially in plants, is given, and the general conclusion reached 

 that the sex of the plant is not determined by the production of two kinds of eggs which are 

 distinctly male-producing or female-producing or by two kinds of pollen grains, as believed 

 by Bateson and Correns, but that there are gametes of "graded potencies," some prevailingly 

 or exclusively male-producing, others prevailingly or exclusively female-producing, others 

 more strictly monoecius-producing. — Chester A. Darling. 



828. Zeleny, Charles. The mutational series, full to bar to ultra bar, in Drosophila. 

 Anat. Rec. 17: 336. Jan. 20, 1920.— [Author's abstract of paper read before American Society 

 of Zoologists, St. Louis, December 30, 1919.]— Ultra-bar appeared in a single male in the sec- 

 ond generation of downward selection in white bar on November 20, 1917. The stock estab- 

 lished from it averaged 23 facets in the males as opposed to 75.6 facets in the bar stock from 

 which it was derived and 849.8 facets in full eye. It has remained constant since that time 

 except for the appearance of a few additional mutations. The interest in this mutant lies in 

 the following facts. It is not due to an accessory factor, but is a change in the bar gene itself. 

 The changed gene produces a somatic effect which is an intensification of that produced by 

 bar. This effect is in the direction of selection. The dominance is greatly increased. Ultra- 

 bar and the various other races of bar furnish unusual material for a quantitative study of 

 both germinal and environmental factors. — Charles Zeleny. 



829. Zeleny, Charles. The tabulation of factorial values for eye-facet number in the 

 bar races of Drosophila. Anat. Rec. 17: 337-338. Jan. 20, 1920.— [Author's abstract of paper 

 read before American Society of Zoologists, St. Louis, December 30, 1919.] — In working up the 

 data obtained in a study of the germinal and environmental factors affecting eye-facet number 

 in the bar races of Drosophila, it became evident that the demands of biological analysis were 

 not adequately met by the system of arrangement in classes with equal facet numbers. It 

 has been shown by Krafka that the effect of temperature upon the mean facet value of a stock 

 is approximately proportional to the mean value of that stock. A change of one degree in 

 temperature in a 200-facet stock produces ten times as much change in facet value as it does 

 in a 20-facet stock. The probability that other factors affecting facet number may act in a 

 similar way is discussed, and the conclusion is reached that a tabulation in classes with equal 

 facet numbers does not give as close an approximation to true factorial values as a tabulation 

 in which the range of each class is equal to a definite fixed per cent of the mean facet value of 

 its class. In the latter case the classes may be taken to represent equal factorial values 

 though the facet ranges are unequal. The variation constants can then be put directly in 

 factorial units. Such a scheme is especially valuable in the graphic representation of selec- 

 tion data in which the mean of the unselected stock is taken as the point of departure, and any 

 facet value can be represented as plus or minus a certain number of factorial units from the 

 mean of the unselected stock. — Charles Zeleny. 



830. Zeleny, Charles. Forty-two generations of selection for high- and low-facet num- 

 ber in the white bar-eyed race of Drosophila. Anat. Rec. 17: 338-339. Jan. 20, 1920.— [Au- 

 thor's abstract of paper read before American Society of Zoologists, St. Louis, December 30, 

 1919.] — Following the discovery of the pronounced effect of temperature upon eye-facet num- 

 ber in Drosophila, a careful control of that factor has made possible a better analysis of the 

 results of selection than that obtained in the earlier work of Zeleny and Mattoon, May and 

 Zeleny. The present paper deals with forty-two generations of selection in a white-bar race. 

 With accurate temperature control it is possible to isolate the occasional mutants as they 

 arise and to demonstrate thai if they are not included in the series, selection ceases to be effec- 

 tive after three to five generations. Crosses between 1 lie hich and low lines confirm the 



