NOTES AND ABSTRACTS. 



403 



Neillia and Stephanandra. By S. Mottet {Rev. Hort. vol. xci. pp. 236-238 ; 

 1 fig.). — Neillia sinensis is an ornamental shrub well worth a place in the garden 

 on account of its graceful foliage and sprays of pink flowers. N. affinis, N. 

 longiracemosa, N. thibetica, and N. ribesoides are recent introductions from 

 Sechwan. N. pauciflora is a native of Yunnan. All the above have dark-pink 

 flowers. Another new arrival is Stephanandra chinensis from Kiangsi, which 

 differs from S. incisa by having larger and more deeply incised leaves. — S. E. W . 



Nitrates, Nitrification of Acid Scils, Effects of Lime, Crops, and Moisture on. 



By H. A. Noyes and S. D. Conner {U.S.A. Jour. Agr. Res. xvi., No. 2, Jan. 

 1919, pp. 27-43 ; 9 plates). — Experiments were made with five typical acid soils 

 treated with calcium carbonate, acid phosphate, and complete fertilizer, cropped 

 with wheat and clover. Control experiments were also made without crops or 

 fertilizer, and with varying quantities of water. It was found that CaC0 3 

 increased in a marked manner the nitrification of the five soils. The degree of 

 saturation of the soils affected the nitrates present. More nitrate was found in 

 soil kept half-saturated with water than in soil a quarter saturated. Fully 

 saturated soils (for ten months) contained no nitrates, and no nitrates were formed 

 with ammonium sulphate. The bacterial flora of each soil was different, and 

 CaCO s increased the number of aerobic organisms. In general, the greater the 

 aerobic bacterial content and the nitrifying power of the soil, the larger the crop- 

 yields. 



A bibliography is appended. — A. B. 



Nitric-Nitrogen Accumulation in Scil, Influence of Salts on the. By J. E. 



Greaves, E. G. Carter, and H. C. Goldthorpe {U.S.A. Jour. Agr. Res. xvi., 

 No. 4, Jan. 1919, pp. 107-135). — Salts which occur in soils, or which may be ap- 

 plied to them, influence the number, species, and activity of the micro-organisms 

 in the soil. These factors in turn are reflected by the yields obtained from the 

 soil. The objects of the investigation were : (1) To determine the relative 

 toxicity of various substances in the soil as measured by bacterial activities ; 

 (2) to determine the stimulating influence of various substances upon bacterial 

 activity, and the manner in which the stimulus is exerted. The soil used was 

 sandy loam with a high percentage of acid-soluble constituents. Calcium and 

 magnesium carbonates present in great amounts. 

 The authors' conclusions were as follows : 



The toxicity of chlorides, nitrates, sulphates, carbonates of Na, K, Ca, Mg, 

 Mn, and Fe, as determined by nitrification, is determined by the specific salt, 

 not by the electro-negative ion, as in the case of ammonifiers. Except MnCl 2 , 

 MnS0 4 , NaCl, FeCl 2 , and FeS0 4 , the salts all became toxic at a lower concentration 

 to the nitrifiers than to the ammonifiers. 



The common alkalies CaCl 2 , Na 2 S0 4 , Na 2 C0 3 , CaNO a are very toxic to the 

 nitrifying organisms, and reduce greatly the nitrogen accumulation in such a 

 soil. 



The compounds which are the strongest plant stimulants are also the most 

 active in increasing the nitrogen accumulation, and it seems probable that the 

 effect upon the plant is due mainly to the action of the compound upon the 

 bacteria, which in turn render available more plant food. 



Magnesium nitrate, ferric nitrate, calcium nitrate, and manganous nitrate 

 are very active stimulants of the nitrogen-fixing organisms. In some cases these 

 compounds increase nitrogen fixation many times over that in the normal soil. 



The ammonifying powers of a soil containing alkalies are a better index of 

 its crop-producing powers than are the nitrifying powers. — A. B. 



Nitrification III. The Isolation and Description of the Nitrite Ferment. By 



Augusto Bonazzi {Bot. Gaz. vol. lxviii., No. 3, Sept. 1919, pp. 194-207; with 

 1 plate). — In this paper are described the organisms responsible for the for- 

 mation of nitrites in the Ohio soils, and the methods used in their isolation. 

 Z. Winogradsky classified the cocci which convert soil ammonia into nitrates 

 as follows : — 



(i) Nitrosomonas — from the Orient or Old World. 



(ii) Nitrococcus — from the Occident or New World. 



No samples of soil from the North American Continent were studied by him, 

 all his material coming from South America. 



The organisms isolated by the present writer appeared during the process 

 of full nitrification as small granules contained in a thick gelatinous mass. This 

 gelatinous layer surrounding the cells is of the same thickness as their diameter. 

 With iodine it acquires a bluish tinge, while the embedded cells stain golden 

 yellow. 



