318 BOTANICAL GAZETTE [OCTOBER 
colors are recessive to the full colors, but more commonly the lighter shades 
are epistatic to the intense ones and are interpreted as the result of a partial 
inhibitor or “palliator”; there is similar epistasis of the lighter stem colors to 
the darker; two inhibiting factors produce definitely localized effects in the 
flower, one affecting the central region of the flower, the other the periphery. 
In all of these unit characters the expected Mendelian ratios were obviously 
present except in several instances of ‘“‘repulsion” and of partial coupling. 
Thus magenta was never found associated with the short style, and a partial 
coupling between magenta flower color and green stigma seems to indicate 
that there is a segregation on the plan 7:1:1:7 in one of the sexes, while in the 
other sex the segregation follows the usual plan 1:1:1:1. 
The occurrence of dominant and recessive white in the flower color of the 
different varieties presents an interesting situation. In the varieties first 
investigated, the dominant white was always associated with red stems and 
the recessive white with green stems. An exception to this rule exists in the 
case of the variety “Pearl,” in which dominant white and green stems are 
combined. KEEBLE and PELLEW! now report an exception in the opposite 
direction in “‘Snow King,” a red-stemmed variety with either dominant or 
recessive white flowers. Crosses between this variety and various colored 
varieties gave different results according as the particular individual of “Snow 
King” used in the cross chanced to be dominant, heterozygous, or recessive 
in regard to a dominant white factor W. The heterozygous whites when 
crossed with colored varieties gave white and colored, 1:1 in the F;, and these 
F, whites when self-fertilized produced an F, which in each case -_ approxi- 
mated the expected ratio, 13 white: 3 colored—GrorGE H. SHUL 
An inhibiting factor in oats.—Nusson-Eutes describes a number of 
instances in which mutants resembling the wild oats (Avena fatua) have 
appeared in his cultures of numerous cultivated varieties of Avena sativa, 
the coefficient of mutation being about 1 in 10,000. These atavists had 
approximately the same congeries of characteristics regardless of the char- . 
acteristics of the varieties in which they were discovered. Most frequently 
they were found in heterozygous combination with the cultivated varieties, 
but sometimes also in the pure extracted forms. That these could not have 
been the results of crosses with the wild oats is proved by the fact that when 
they appeared in a variety having white or yellow glumes, the atavist retained 
this recessive character. The heterozygotes proved to be in all cases inter- 
mediate between the atavists and the particular varieties in which they 
appeared. The fact that the atavistic type differs in each case by 2 single 
unit character, so that the whole group of wild characters appears in their 
EEBLE, F., and PELLEw, Miss C., White-flowered varieties of Primula sinensis. 
tea Ceaictice Ii1-5. 1910 
5 Nitsson-Ente, H., Ueber Fille spontanen higoeate eines Hemmungsfaktors 
beim Hafer. Zeit. Ind. ‘Abuiasn. Vererb. 521-37. pl. I. I91I. 
