1915] ‘CURRENT LITERATURE 261 
calls this interpretation in question. For example, in Festuca spadicea these 
persistent sheaths are found in the soil, where protection from transpiration is 
of little importance. A more striking observation was made on Festuca varia, 
e, 
JEROscH postulates that these hairs are water-absorptive organs. Such an 
observation needs oe corroboration, as the author frankly recog- 
nizes.—H. C. Cow 
Soil studies.—E. E. FREE of the U.S. Bureau of Soils has brought together 
es essential features of our knowledge of soil physics in admirable form for 
e by physiologists and ecologists. The material is treated under the 
fell wtie heads: the physical condition of soils, the movements of soil water, 
soil water and the plant, the physical constants of soils, and soil temperature. 
FREE has also published an elaborate paper on soil movement by wind.’ 
While this treatise will be of value in the first instance to physiographers, it 
will also be of great interest to all ecologists who are interested in the vegeta- 
tion of such wind deposits as sand dunes or loess. Among the topics treated 
are the mechanics of wind translocation, drifting sand and sand dunes, dust 
storms and dust falls, atmospheric dust, geologic formations of eolian origin, 
and volcanic dust as soil material. At the close is a remarkably se 
bibliographical index of eolian geology; in the compilation of this index Fre 
was aided by S. C. Sruntz.—H. C. CowLes 
Defoliation and wood structure.—In recent years many trees of the 
European larch in the English Lake District have been repeatedly defoliated 
by the large larch sawfly. Some of the trees have been studied by Harper's 
to determine the influence on wood structure. Such defoliation means starva- 
tion to a greater or less degree, and starvation affects both the amount of growth 
and the structure of the wood. In the lower parts of the tree, where the rings 
ordinarily are narrower than they are above, growth may cease altogether; 
higher up, where there is more growth, the rings may not completely encircle 
the tree. Even before this effect is seen, there is a reduction in the wa 
thickening of the autumn wood. This situation is related to an actual lack 
in the foods necessary to build up these tissues to the usual amount.—H. C. 
Cow Les. 
*s FREE, E. E., Studies in soil physics. Plant World 14:29-39, 59-66, 110-119, 
164-176, oi aie IQIr 
“Fare, E. E., The movement of soil material by the wind. U.S. Bureau of 
Soils, Bull. 68. pp. 72. pls. 5. 
*s Harper, A. G., platting its effects upon the growth and structure of the 
wood of Larix. Ann. Botany 27:621-642. pls. 2. figs. 2. 1913. 
