514 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
Sievekingia Shepheardii (Bof. Mag. t. 8635). — Colombia. Nat. Ord. Orchida- 
ceae, tribe Vandeae. Herb, epiphytic. Pseudo-bulbs 2-foliate. Leaves acuminate, 
5-8 inches long. Scape erect, 4 inches long, many-flowered, yellow, finch across. 
G. H. 
Sodium Salts in the Soil, The Effect of, upon Plant Growth. By F. B. Headley, 
E. W. Curtis, and C. S. Scofield {Jour. Agr. Res. vol. vi. No. 22, Aug. 1916, 
pp. 857-870 ; 8 figs. — Attempts were made to utilize for crop production 
certain salt lands at Fallon, Nevada, U.S.A., and experiments were devised to 
determine the limit of tolerance of the crop plants in such soil to the common 
salts of sodium. 
It was found that only a part of the salt added to the soil in pot cultures 
could later be recovered from it by water digestion ; this apparent loss of salt 
was greater in the case of sodium carbonate and sodium sulphate than with 
sodium chloride. 
When sodium carbonate was added to a soil, the absorption was greater in 
fine soil rich in organic matter than in sand. 
The carbonates and bicarbonates of sodium are mutually interchangeable 
in the soil, and the toxicity of the soil solution appears to depend upon the quan- 
tity of the basic radical held in the soil, regardless of the form of the acid radical. 
In the case of the soil from the salt land, the proportion of recoverable salt, 
which would reduce by one half the growth of wheat seedlings, was, for the car- 
bonates, 0-04 per cent, of the dry weight of the soil ; for the chlorides, 0-16 per 
cent. ; and for the sulphates, 0*35 per cent. 
The proportion of recoverable salt which prevented germination of wheat 
was, for the carbonates, 0-13 per cent. ; for the chlorides, 0-52 per cent. ; and for 
the sulphates, 0-56 per cent. — A. B. 
Soil, Actinomycetes in, A Possible Function of. By H. J. Conn [U.S.A. 
Exp. Stn., New York, Tech. Bull. 52, March 1916, pp. 1-11). — The author 
considers that Actinomycetes are active in the decomposition of grass roots, and 
finds that in general more colonies of Actinomycetes are present in sod soil than 
in cultivated soil. The results of plate cultures show the proportion of 38 per 
cent, of the total flora of sod soil, but only 20 per cent, of the total flora of culti- 
vated soil consisted of Actinomycetes. It appears that the numbers are even 
greater in old grass land than in grass land of two or three years' standing. — A . B. 
Soil, Bacteriological Studies of a, under Different Cropping for Twenty-five 
Years. By P. L. Gainey and W. M. Gibbs (Jour. Agr. Res. vol. vi. No. 24, 
Sept. 1916, pp. 953-975)- — The plots have been under cultivation since 1889, 
and are located in the land of the Missouri Experimental Station. Each plot 
consists of one -tenth of an acre and is surrounded by a path 3 feet wide. 
The following is a summary of the results : — 
1 . The agricultural methods practised upon these plots have brought about 
marked differences in the number of organisms contained in the soil. The 
soil under continuous corn and wheat contains relatively low numbers of bacteria, 
in the absence of manure and fertilizers. The presence of manure largely in- 
creases the number of bacteria upon continuous wheat and corn lands. 
2. The agricultural practices have produced no appreciable effect upon the 
ability of the soil and its organic life to liberate ammonia from cotton-seed meal. 
3. The ability of the soil complex to oxidize ammonia nitrogen to nitrate 
nitrogen has been materially altered by the methods under study. Continuous 
corn and wheat with no manures or fertilizers have brought about a relatively 
low oxidizing power in the soil complex. The addition of manure largely raises 
the oxidizing power upon such land. — A . B. 
Soil Fumigation, A New Method. By J. S. Houser (Jour. Econ. Entom* 
ix. p. 285, April 1 916). — Carbon bisulphide poured into the soil is quickly 
absorbed by it, and the fumes are liberated but slowly. The author proposes to 
blow the fumes into the soil (for killing ants and other soil insects) by placing 
the carbon bisulphide in a wide-mouthed bottle through the cork of which two 
tubes pass, one reaching into the liquid at the bottom, the other only a short distance 
into the bottle. To the former a pump is attached, and air charged with the 
carbon-bisulphide fumes is driven out of the other through an attached tube into 
the soil by working the pump. — F, J. C. 
Soil Micro-organisms, Longevity of, Some Factors Influencing the. I By 
W. Giltner and H. V. Langworthy (Jour. Agr. Res. vol. v. No. 20, Feb. 
1916, pp. 927-942). — Experiments were made to determine whether an organism 
