No. 2, November, 1920] GENETICS 99 



his earlier papers. — The analysis of the four unselcctcil gencrat ions ;i( Ihe end of tin- selected 

 line showed that high and low grade parents gave rise to the same grade of offspring. Hence 

 the strain was homozygous. — F. Payne. 



709. MuLLEit, H. J., and E. A i. n:\nuHfi. The rate of change of hereditary factors in 

 Drosophila. Proc. Soc. Exp. Biol. Med. 17: 10-14. 1919. — Rate of mutation in Drosophila 

 melanogaeter was determined by observing rate of occurrence of sex-linked lcthals, because 

 lethal mutations arc much more frequent than non-let hals. (In the present experiment, in 

 which 33 lcthals — of which -1 or 5 were scmi-lcthals — were observed, no non-lethal mutations 

 were noticed.) — Sex-linked lcthals were found to occur in 5 out of 445 females (1 in 90) at 

 66°F., and in 13 out of 517 females (1 in 40) at 80°F. The value for Q J0 for mutation is, on this 

 basis, between 2 and 3, as is usual for chemical reactions. The average rate of mutation was 

 1 in 53. This would mean that one fly in every 13 should contain a lethal mutation in some 

 chromosome or other. A new lethal should occur in each X chromosome once in every 100 

 generations (4 years), and each individual factor should mutate on the average not oftener 

 than once in 2000 years. — Alexander Weinslein. 



710. Nienburo. [German rev. of: (1) Bensattde, Mathilde. Recherches sur le cycle 

 evolutif et la sexualite chez les Basidiomycetes. (Researches on the evolutive cycle and sex- 

 uality in the Basidiomycetes.) 156 p., pi. 1-8, 80 fig. (Dissertation.) Nemours, 1918. (2) 

 Kniep, Hans. Uber morphologische und physiologische Geschlechtsdifferenzierung. (Unter- 

 suchungen an Basidiomyzeten.) On the morphological and physiological sex differentiation. 

 (Studies on Basidiomycetes.) Verhandl. Physik.-med. Ges. Wiirzburg. 18 p. 1919.] Zeit- 

 schr. Bot. 12: 173-175. 1920. 



711. Nilsson-Ehle, H. Uber resistenz gegen Heterodera Schachti bei gewissen gersten- 

 sorten, ihre Vererbungsweise und Bedeutung fur die Praxis. [On resistance to Heterodera 

 Schachti in certain varieties of barley, its method of inheritance and significance for agricul- 

 tural practice.] Hereditas 1: 1-34. 4 fig. 1920. 



712. Pearl, Raymond. A contribution of genetics to the practical breeding of dairy cattle. 

 Proc. Nation. Acad. Sci. [U. S.] 6: 225-233. 1 fig. April, 1920.— This paper presents a brief 

 resume of the conclusion drawn from the study of Jersey registry-of -merit sires relative to 

 what these sires did in transmitting milk yield, butter-fat percentage and butter-fat to their 

 offspring. The measure of this performance is daughter's production minus dam's production 

 equals the genetic worth of the sire for transmitting milk yield, etc., to his offspring. — Trans- 

 mitting power of 224 sires for butter-fat are presented in this paper. The reader is referred 

 to the complete paper from the Maine Station for the other detailed results. — Certain of the 

 conclusions are: (1) There are 224 Jersey registry-of-merit sires which meet the requirements 

 of this performance test for their transmitting qualities in milk production. One hundred 

 and five of these sires, or less than one-half, raise the milk production of their daughters over 

 that of the dams of these daughters. The largest number of daughter-dam pairs is 39 for the 

 sire Hood Farm Pogis 9th, 55552. Of those sires which have a large number of pairs, Hood 

 Farm Torono 60326 with 34 pairs stands first in his transmitting qualities raising the milk 

 production of his daughters on the average 2620.1 pounds. — (2) Two hundred and twenty-five 

 sires are included in the table giving the sires which met the requirements of the daughter- 

 dam performance test for transmitting qualities of butter-fat percentage. Out of this number 

 101 sires raised the butter-fat percentage of their daughters' milk as compared with the butter- 

 fat percentage of the dams of these daughters. The leading sire in this butter-fat percentage 

 performance test was Clear Brook Chief 746S5 raising his daughters on the average 1.338 per 

 cent of butter fat. This sire had two daughter-dam pairs. Hood Farm Pogis 9th leads in 

 number of daughter-dam pairs with 42. This bull raised the butter-fat percentage of his 

 daughters on the average of 0.243 per cent over the butter-fat percentage of the dams of their 

 daughters. — (3) The sires mentioned as superior in the milk-transmitting ability, Hood Farm 

 Torono and Spermfield Owl, do not check up so well in their ability to transmit high butter- 

 fat percentage. Hood Farm Torono caused his daughters on the average to be 0.225 per cent 



BOTANICAL ABSTRACTS, VOL. VI, NO. 2 



