1921] CURRENT LITERATURE 407 
epidermal, and both intercellular and intracellular. In the protocorm “it 
seems to be always present in an intercellular position in the central tissues.” 
The demonstration of the fungus in this structure inclines the author toward 
“BOweERr’s suggestion” concerning the phylogenetic importance of the proto- 
corm. The most interesting thing to the reviewer is Hortoway’s discovery 
that the germinating spore sometimes develops a filament before the “primary 
tubercle” stage of TrEusB is reached. This fact a some light upon 
the phylogenetic history of the Lycopodium protha 
In a discussion of the cause of such a variety of yee: in the prothallia of 
tor 
He suggests that the primary tubercle may af a secondary growth rather 
than a primary one.—E. A. SPESSARD. 
Wilting coefficient studies—Considerable surprise was expressed at the 
announcement by Briccs and SHantz of the “wilting coefficient” an 
important critical factor in the relation of soil moisture to the plant, and at 
their statement that the wilting coefficient was practically the same for all 
classes of plants and showed little or no variation in response to atmospheric 
changes. Many seemed to doubt the accuracy of these statements, and several 
unsuccessful attempts were made to demonstrate a relationship between the 
evaporating power of the air and the wilting coefficient. ULL” showed 
rather conclusively that the wilting coefficient is a function of the movement 
of water in the soil rather than a lack of gradient of forces tending to move 
the water toward the plant. As a function of the soil finding an expression 
through plants, rather than a function of the relationship of the forces exerted 
by the plant, it does not seem surprising that the wilting coefficient is much 
the same for all plants and for all atmospheric conditions. 
Attacking the problem from a somewhat different angle, L1vincsTON and 
Koketsvu*3 show even more conclusively that the wilting coefficient is a func- 
tion of water movement in the soi]. These workers made use of small porous 
porcelain cones or “‘soil-points” which, while dry, were thrust into the soil. 
At the end of a suitable period they were withdrawn, and by weighing the 
amount of water absorption was determined. The data obtained indicated 
that at permanent wilting the water supplying power of the soil was the same 
for the different plants used and also for different soils within certain limits. 
They regard this present report a tentative and preliminary one, but in the 
soil-point method there seems to be much promise of a complement to the 
porous cup atmometer investigations of the moisture conditions of the atmos- 
phere.—Gro. D. FULLER 
- Ss C. A., Measurement of the surface forces in soils. Bort. Gaz. 62:1-29 
Jigs. 5 
8 Liv. on, B. E., and Koxetsv, R., The water ts power of the soil as 
elated to ‘oe eiliies of plants. Soil Science 9:469-485 
