306 GENETICS [Bot. Absts. 



shown that: (1) A limiting population will be reached in all cases, which will thereafter 

 remain constant; (2) The limiting population had the peculiarity that the homozygotes in 

 it will be proportional to each other in pairs; (3) Such populations have other numerical 

 peculiarities. The importance of these results to practical breeding is pointed out and a 

 method formulated by which it is possible to derive immediately the limiting proportions in 

 a population when the number of factors and the type of mating is known. — L. Baas Becking. 



2086. Becking, L. G. M. Baas. Over Limietverhoudingen in Mendelsche populaties. 

 [Limiting proportions in Mendelian populations.] Genetica 1: 443^456. 4 fig- Sept., 1919. — 

 Reviews papers by Jennings, Henkels, Wentworth & Remick, Hardy, Bruce, and Rob- 

 bins. Formulae are derived and graphs constructed to homologize the work of these authors 

 for: (1) Panmixia for 1,2 and 3 factors (Hardy, Becking); (2) Autogamy for 1 or more fac- 

 tors (Jennings) ; (3) Combined allogamy and geitonogamy for 1, 2, and 3 factors (Henkels) ; 

 and (4) Different forms of selective mating (Bruce, Robbins, Wentworth and Remick). 

 From the formulae and graphs the limiting proportions in any population in which the type 

 of mating is known can be easily and immediately derived. As shown by the graphs the rate 

 at which the limits are approached varied widely with the type of mating. — L. Baas Becking. 



2087. Beeson, M. A. Report of agronomy department. Oklahoma Agric. Exp. Sta. Rept. 

 1918: 14-22. 1918. — Progress report of selection experiments and variety tests with farm 

 crops. States that improved seed distributed through Oklahoma Seed Growers' Association 

 has materially increased yields and improved quality. — H. K. Hayes. 



2088. Bhide, R. K. Probable material for the study of the experimental evolution of Oryza 

 sativa, var. plena Prain. Agric. Jour. India 14: 494-499. 1919. — Oryza saliva, var. plena 

 Prain, the "double-grain paddy" is a variety of rice cultivated in Bengal. Usually a certain 

 proportion of the spikelets of the panicle contain from 2 to 5 grains each. Almost every 

 spikelet has from 2 to 5 ovaries in the flowering stage. The number of well developed grains 

 per spikelet is often only from 1 to 3; as probably all of the ovaries are not in a stage to be 

 fertilized at the same time. In a plot of this variety, it was found in rare instances, that the 

 topmost spikelets on a few branches of the panicle had only a single ovary with 4 or more 

 stigmas, two or more ovaries being then united together. The number of stamens in each 

 spikelet is usually 6, but in rare instances it was found to be 7 or 8, thus indicating a slight 

 tendency in the stamens to increase their number. Sometimes the spikelets showed a ten- 

 dency to increase the flowering glumes and pales. A few plants showed a slight tendency 

 to form clusters of spikelets near the tips of the branches. In ordinary rice the spikelets 

 consist of two small empty glumes which stand on the outside of the remaining flowering 

 glume, and glume-like pale, which normally encloses two lodicules, six stamens, and a soli- 

 tary pistil, with two styles and hairy stigmas. Whether these overlapping variations are 

 due to some temporary disturbance in the plants, caused by an abnormal season, or they are 

 the beginnings of progressive changes, has yet to be proved. It is probable that the produc- 

 tion of the additional flowering glumes, pales, stamens, etc., but the double grain paddy might 

 be a retrograde step. The author is looking for other stages in order to bring about an ex- 

 perimental evolution of the double grain paddy from the ordinary variety without the help 

 of crossing. — F. M. Scherlz. 



2089. Blackwell, C. P., and R. E. Currin. Work with field crops in South Carolina. 

 South Carolina Agric. Exp. Sta. Rept, 1918: 18-20, 38-39, 40, 41, 191S. — Progress report of 

 variety tests and selection experiments. Found pollen from barren stalks gives progeny 

 with a ratio of 1 barren to 2.56 normal stalks. — H. K. Hayes. 



2090. Bos, J. Ritzema. [Rev. of: Marissen, J. Z. Ten Rodengate. Algemeene Plant- 

 endeelt. (General plant breeding.) 5 ed., revised by J. Elema. J. V>. Wolters: Groningen, 

 1919.) Tijdschr. Plantenz. 25: 159-160. 1919. 



