NOTES AND ABSTRACTS. 
235 
is extracted with successive doses of dilute acid. The amounts of phosphate 
thus extracted when plotted show that the action is not that which would result 
were the soil simply a mixture of inert materials including phosphates. 
Russell and Prescott in the present paper show that the action between dilute 
acid and the soil is in two parts, viz. a direct and a reverse action. The direct 
action results from absorption of P2O5 from the soil by the acid : the reverse 
action results from adsorption of P 2 0 5 by the soil from the solution . The amount 
of P2O5 extracted is therefore not ' ' available ' ' phosphate but merely an analytical 
result. Different acids at equivalent concentrations have much the same direct 
effect : but the extent of the reverse or adsorptive action varies with different 
acids, being notably smaller in the case of oxalic and citric acids than with sul- 
phuric, hydrochloric, or nitric acid. Hence the net action of citric acid is due 
not to greater solvent action, but to greater power of reducing adsorption. The 
great variations in " available " P 2 0 5 as usually determined and the absence of 
correlation between these analytical results and the crop results are therefore 
due to variations in the nature of the acid and temperature and other conditions 
of experiment. On the same type of soil, with the same concentration of one 
acid and with other conditions the same, comparable results are obtained. 
The reverse (adsorptive) action is eliminated by a diffusion method described in 
the paper.—/. E. W. E. H. 
Phytophthora Genus, Studies of the. By J. Rosenbaum {Jour, Agr. Res. 
viii. Feb. 191 7, pp. 233-276 ; 7 plates). — No definite criteria for the identification 
and separation of the various species of Phytophthora are known, and the author, 
with a view of supplying such information, obtained 11 out of the 13 species 
already described and studied their behaviour from pure cultures on artificial 
media. He found that the various species react differently on the different 
media, and made careful measurements of the conidia and chlamydospores, 
of the various types, the last named being especially useful in delimiting the 
species. A tentative table for the separation of the species is given, in which 
the genus is divided into three main groups. 
A. C actor um Group. Oogonia with antheridium at side : P.Cactorum) P.Fagi; 
P. Syringae ; P. Nicotianae. 
A. A. Phaseoli Group. Oogonia with antheridium at the base : P. Phaseoli ; 
P. Arecae; P. erythroseptica; P. parasitica; P. infestans. 
A. A. A. Faberi Group. Antheridium unknown: P. Faberi; P. Jatrophae. 
Similar tables for the identification and separation of the species of such 
genera as Pythium, Peronospora, Plasmopara, Sclerospora, and Pythiacystis 
are greatly needed. — A. B. 
Pine Lodgepole in the Rocky Mountains, Utilization and Management 
of. By D. T. Mason (U.S.A. Dep. Agr., Bull. 243, July 12, 1915). — Lodgepole 
pine (Pinus contorta) is the most important timber tree of the Rocky Mountains 
between Northern Colorado and Central Montana. Once considered almost 
worthless, it now brings $10 to $100 an acre in National Forest timber sales. 
The wood of lodgepole is straight-grained, with narrow rings in which the 
resinous bands of summer-wood are conspicuous, though relatively small when 
compared with the spring-wood. It is more resinous than eastern white pine 
(Pinus Strobus), but less so than the yellow pines of south and west. It varies 
from almost white to light yellow or yellow-brown, with a tinge of red in the 
heart-wood. Its specific gravity (even dry) is about 0*38, and its weight varies 
from 25 to 30 lb. a cubic foot. 
The wood is fairly soft — about the same as eastern white spruce (Picea 
canadensis) — and is easily worked. Though not so strong as Douglas fir of the 
Pacific coast (Pseudotsuga taxifolia), a heavier wo*od, tests made by the Forest 
Service show it to be practically as strong as western yellow pine (Pinus ponder osa), 
and stronger than Engelmann spruce (Picea Engelmanni) and Alpine fir (Abies 
lasiocarpa), three woods of more nearly its weight. 
Tests made on lodgepole pine and western red cedar (Thuja plicata) — telephone 
poles cut green and seasoned — showed lodgepole pine to be the stronger, both in 
cross-bending and in compression parallel and perpendicular to the grain. The 
strength of fire-killed lodgepole pine poles was found to be approximately the 
same as that of red cedar poles cut green and seasoned. 
Lodgepole pine is not durable in contact with the soil, but is easy to treat 
with preservatives. — A. D. W. 
Pine Moth, The Zimmermann. By J. Brunner (U.S.A. Dep. Agr., Bull. 295, 
October 28, 191 6). — This moth (Pinipestis zimmermanni) is very destructive to 
conifers, and especially to Pinus ponderosa in various sections of the west, and P. 
