242 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
supports twenty species belonging to eleven genera. Many of these beetles are 
to be found only on the Scots pine, and others of them prefer it to their other 
.hosts, such as spruce. — A. D. W. 
Seed Production of Western White Pine. By Raphael Zon (U.S.A. Dep. Agr,, 
Bull. 210, April 17, 1915). — The age of the trees evidently has an effect upon the 
amount and quality of seed produced. Thus the younger trees, ranging from 
72 to 100 years of age, have produced a larger quantity of germinable seed than 
the older trees. 
The relation between the length of the cone and the size of the seed (the 
number of seeds in a pound) is clearly shown. Thus the longest cones, 8 inches 
and over, yielded about 22,000 seeds to the pound, while cones 5 inches long 
occasionally yielded as many as 57,000 seeds to the pound. 
The vigour of growth apparently influences favourabty the amount and 
quality of seed produced. 
While a relation between the size of the seed and its germinative vigour is 
not clearly brought out, yet there seems to be a tendency for the larger seeds to 
have the highest germinative vigour. — A. D. W. 
Seeds, Temperature and Life Duration of. By James F. Groves (Bot. 
Gaz. vol. lxiii. No. 3, March 1917, pp. 169-187). — The investigations described 
were carried out with the idea of seeking to determine " the extent to which a 
study of the laws of the life duration of seeds at high temperatures (50°-ioo° C.) 
will explain the process of degeneration of air-dried seeds at ordinary storage 
temperatures." The experimental results obtained makes possible a quantitative 
statement of the significance of various storage conditions, especially moisture 
content and temperature upon the longevity of seeds. — R. J. L. 
Shortleaf Pine : Its Economic Importance and Forest Management. By 
W. R. Mattoon {U.S.A. Dep. Agr., Bull. 308, November 22, 1916). — Shortleaf 
pine is admirably adapted to pure plantations, which are strongly recommended 
over any kind of mixture in starting young forest stands. Shortleaf may, how- 
ever, be planted in mixture with heavier-foliaged species of slower growth — for 
example, sugar maple and such durable and valuable wood as red juniper. The 
red pine and western yellow pine are not successful in mixture with shortleaf, 
because of the attacks of Aecidium Pint, a rust fungus. Pure plantations of 
shortleaf promise larger financial returns than any other form. Mixed stands 
afford better protection against large losses from disease and insect ravages, as 
well as a variety of wood for use on the farm and to supply markets which may 
offer better returns for such sales. — A. D. W. 
Soil Bacteria, Influence of Barnyard Manure on. By J. E. Greaves and 
E. G. Carter (Jour. Agr. Res. vi. pp. 889-926 ; Sept. 1916). — The authors found 
that the quantity of manure, and of water, and the cropping influenced the 
bacterial content of the soil. In the particular calcareous soil experimented 
with, the application of five to fifteen tons of manure increased both the am- 
monifying and the nitrifying powers of the soil, as did the application of thirty 
inches of irrigation water. Forty inches of water, however, reduced the ammoni- 
fying powers. A direct relationship was found between the number of bacteria, 
the ammonifying and nitrifying power, and the crop production on soil receiving 
no manure, five tons, and fifteen tons an acre, while the bacterial activities 
of soil receiving varying amounts of water were closely correlated with the crop 
produced. The ammonifying and nitrifying powers of fallow soils were slightly 
higher than those of cropped soils. — F. J. C. 
Soil Bacteria, The Influence of Crop, Season, and Water on. By J. E. Greaves, 
R. Stewart, and C. T. Hirst (Jour. Agr. Res. ix. May 1917, PP- 293-341). — 
It is of the utmost importance that the quality and quantity of plant food 
rendered available during the season should balance that required by the growing 
plant, so that the maximum yield may be obtained with the minimum loss of 
soil fertility. Most of the changes which take place in the soil are due to bacteria, 
and the speed with which these changes occur is governed, amongst other factors, 
by the season of the year, the crop, and the water in the soil. 
The authors, after reviewing concisely the previous work done by other 
investigators on the influence of moisture, the influence of the crop, and the 
influence of the season, and after numerous experiments, arrived at the following 
conclusions : — 
The quantity of nitric nitrogen in the surface 6 feet of alfalfa soil is low 
throughout the season, but higher in the autumn than in the spring or summer. 
