1922] CURRENT LITERATURE 341 
several factors in one region of a chromosome have been discovered. NILsson- 
HLE* now claims to have such a case, and calls it “complexmutation.” 
Normal wheat mutates to bearded speltoid, involving a simultaneous change 
in two closely linked factors. Among the F, progeny of normal mutant 
appear a few bearded normal type and beardless speltoid, but only a very few, 
cae to we very close linkage ZS the ve aad peers. Tn Snorer case 
1 41 4 
M. C. Couties. 
= 
Ozark forests.—The Ozark region, as covered by PALMER’ in this recon- . 
noissance, is defined as occupying the southern half of Missouri, a narrow spur 
crossing southern Illinois, the northwestern part of Arkansas, and a long tri- 
angular strip in eastern Oklahoma. The two topographic divisions of this 
uplifted region, lying midway between the higher mountains of the east and 
west, are the flat-topped dome of the northern plateau with an average altitude 
of 300-500 m., and the southern Boston Mountains with a few p 
600 m. It is a hill region surrounded by fertile plains, and possessing a rather 
abundant rainfall. Floristically there are no distinct floras corresponding to 
the topographic divisions, although the southern parts of the region, including 
the Boston Mountains, have a heavier forest growth richer in types than the 
northern, and include such southern forms as Aesculus discolor, Tilia floridana, 
Rhamnus caroliniana, Ilex decidua, and Magnolia acuminata. 
The larger portion of the report is occupied by floristic notes on various 
sections of the flora and on certain genera and species. The author is con- 
vinced that in the region as a whole there is a demonstration of the gradual but 
actual encroachment of forest upon prairie lands.—Geo. D. FULLER. 
Temperature and nodule development.—Using soil temperatures rangi 
from 12° to as high as 40° C., Jones and TIsDALE” have studied the effect of 
these temperatures on the development of nodules by alfalfa, red clover, soy 
beans, and field peas. The results as to the number of nodules developed were 
not so very consistent, but when the dry weight of the nodules was determined, 
it was found that the greatest ee in the case of the soy bean, was at 
24°C. This effect of temp lated with 
a corresponding effect on root and shoot development. It is pointed out in 
the paper that the real question in a study of this kind is not the effect of tem- 
perature on the number of nodules developed by the plants, or on the volume 
of these nodules, but the effect on the amount of nitrogen fixed in the nodules. 
% Nitsson-EuLe, H., —— Allelomorphe und Komplexmutationen beim 
Weizen. Henan tas 1:277-311. 
ALMER, E. J., The forest at of the Ozark region. Jour. Arnold Arboretum 
22216-232, 1921. 
4 Jones, F. R., and Tispae, W. B., Effect of soil temperature upon the develop- 
ment of nodules on ‘the roots of certain legumes. Jour. Agric. Res. 22:17-31. pls. 1-3. 
e 
