No. 1, May, 1921] GENETICS 55 



352. Yasui, Kono. Genetical studies in Portulaca grandiflora. Bot. Mag. T6ky6 34: 

 55-65. PI. 1 {colored), fig. 1. 1920. — Crosses are described between single and double races 

 belonging to 7 color types. Doubleness is dominant. Yellow is due to a yellow flavone deriv- 

 ative, which in the presence of a reducing factor R yields a magenta anthocyanin. White 

 races lack either the chromogen factor C alone or both C and R. Yellow single by white 

 single CCrr X ccRR gives magenta Fi CcRr and Fo by selfing of 9 magenta, 3 yellow, and 4 

 white. Hybrid double magentas CcRrDd by white singles ccRRdd give magenta doubles, 

 magenta singles, white doubles, and white singles in equal numbers. By yellow fsingle they 

 give equal numbers of yellow and magenta {CcRrDd X CCrrdd = iCCRrDd : iCcRrDd : 

 iCCRrdd : iCcRrdd : ICCrrDd : iCcrrDd : ICCrrdd : iCcrrdd). Double whites CcRrDd 

 by pale yellow singles CCrrdd give equal numbers of magenta and yellow doubles and singles. 

 Single scarlet by double white gives magenta double, which mated to single white gives equal 

 numbers of magenta and white doubles and singles. The selfed singles from this give singles 

 only; the selfed doubles, 3 doubles to 1 single. The single mated to the doubles give 1 : 1 

 ratio. — L. L. Bxirlingame. 



353. Zeleny, Chahles. The direction and frequency of mutation in a series of multiple 

 allelomorphs. [Abstract.] Anat. Rec. 20: 210-211. 1921.— Full eye, bar eye, and ultra- 

 bar ej^e in Drosophila melanogasler constitute a series of multiple allelomorphs with decreasing 

 facet number and increasing dominance. Bar arose from full and ultra-bar from bar. Obser- 

 vations were made of the direction and frequency of mutation within pure stocks of the mem- 

 bers of the series. In the full-eye stocks no mutations to bar or ultra-bar were observed dur- 

 ing a period of 6 years among 46,290 counted individuals and among a much larger number of 

 uncounted ones. On the other hand, the reverse mutation from bar to full occurred 52 times 

 among 84,159 individuals or once in 1618, and from ultra-bar to full 5 times out of 8681, or once 

 in 1736. Correspondingly there were only 3 mutations of bar to ultra-bar, including the 

 original mutant, among 84,159 individuals or 1 in 28,053, while the reverse mutation of ultra- 

 bar to bar occurred 3 times in 8681 or once in 2894 and was observed also at another time 

 when the number of individuals examined was not being recorded. Selection for high and low 

 facet number had no effect upon the frequency of any of the mutations. — In this allelomorphic 

 series therefore (1) reverse mutations are much more frequent than the original ones, (2) 

 original progress to ultra-bar is through bar but reversion may go back directly to full as 

 well as through bar, and (3) the frequency of mutation is independent of upward and down- 

 ward selection. — Charles Zeleny. 



354. ZiNN, Jacob. On variation in Tartary buckwheat, Fagopyrum tataricum (L.) Gaertn. 

 Genetics 4 : 534-586. 11 fig. 1919.— This publication records the results of a study of a highly 

 variable, ever-sporting race of Fagopyrum tataricum Gaertn. discovered by the author. A 

 strain was isolated which produced a large number of flowers with supernumerary carpels, 

 the number of carpels varying from the normal 3 to as high as 25. The frequency of abnormal 

 flowers as a rule decreased with increase in number of carpels. In those flowers having more 

 than 6 carpels there was a tendency for an even number of carpels to occur more frequently 

 than an odd number. Associated with the abnormal gynoecia are abnormal perigones with 

 segments varying from the normal 5 to as high as 18. There is some correlation between ab- 

 normal number of carpels and abnormal number of perigone segments. The proportion of 

 abnormal flowers in a given race depends on the environment and is very constant under a 

 given set of environmental conditions. The condition of nutrition had little or no effect on 

 this ratio but high temperature and humidity seemed to increase the proportion of abnormal 

 flowers. Selection for 5 years had no effect on the ever-sporting race. The greatest abnormal 

 development occurred on the 3 lower branches and in the basal region of the terminal raceme. 

 Other variations noted, which seemed to be of the same type, were floral prolifications, often 

 giving rise to syncarpous fruits and fasciation of vegetative parts. — T. O. Sprague. 



355. ZiNN, Jacob. Wheat investigations. 1. Pure lines. Maine Agric. Exp. Sta,. Bull. 

 285. 49 p., 3 pi., 8 fig. 1920.— In 1916, 259 pure lines of wheat were planted at Aroostook 



