No. 1, August, 1920] PHYSIOLOGY 125 



used were gypsum block, magnesium carbonate block, magnesium carbonate and ammonium- 

 magnesium-phosphate block, ammonium sulphate washed agar, and silicic acid jelly. The 

 best results were obtained with Winogradsky's silicic acid jelly. Incubation of all cultures 

 was made at 28 to 30°C. At this temperature cultures were obtained which nitrified as much 

 as 8.04 mgm. of ammoniacal nitrogen in 26 days of incubation. The organism is not motile. 

 Its thermal death point was found to lie between 50° and 55°C, when the vitality of the organ- 

 ism, after heating 5.5 minutes at the required temperature, was tested at rest in Omeliansky's 

 solution containing basic magnesium carbonate. The organism occurs in a large form ^=1.25 ft 

 in diameter and in a small coccus form which the author names (3. He concludes that the meg- 

 alococcus isolated by these methods is very similar to that described by Winogradsky from 

 South American soils and should be classed as a species of the genus Nitrosococcus. — D. H. 

 Rose. 



898. Brackett, R. N., and H. F. Haskins. Report on nitrogen. Jour. Assoc. Official 

 Agric. Chem. 3: 207-217. 1919.— See Bot. Absts. 5, Entry 1003. 



899. Conn, H. J., and J. W. Bright. Ammonification of manure in soil. Jour. Agric. 

 Res. 16: 313-350. 1919. — A foreword by Conn refers largely to previous studies of spore-form- 

 ers and non-spore-formers. Under the title "What soil organisms take part in ammonifi- 

 cation of manure?" Bright shows the predominance of Pseudomonas fluorescens and 

 Pseudomonas caudatus in manured soil and gives the results of an investigation of their func- 

 tion in Dunkirk silt clay loam. — Fresh horse or cow manure was added to the soil in the ratio 

 of 1 : 20. In addition to plate counts direct microscopic examinations were made. Not only 

 was the unsterilized material used but also the sterilized to which was added the pure cultures. 

 The latter was used both separately and in combination. — In unsterilized soil which was 

 kept in pots the data show a rapid increase in non-spore-formers. After 7 days they were 

 never less than 92.5 per cent, while in certain cases they were as high as 97 per cent. The 

 results from experiments conducted in flasks are not so striking, yet the same relation holds. 

 Isolations showed only 2.8 per cent which form spores. — The growth of Ps. fluorescens and 

 Ps. caudatus in sterilized manured soil compared with that of a spore-former, Bacillus cereus, 

 shows that the spore-former had increased in 7 days only 8.3 times while the two former organ- 

 isms had increased respectively 110 and 132 times over the original inoculation. When these 

 three organisms were in association Ps. fluorescens and Ps. caudatus rapidly gained the ascen- 

 dancy over B. cereus, the latter soon sporulating and remaining in this condition. — A test of 

 the ammonia production and cell count in soil of the above three organisms in pure culture 

 shows B. cereus to be the most powerful ammonifier. The two non-spore-forming organisms 

 gave many times more cells per gram of manured soil. However, when the three organisms 

 were grown in association there was no increase in total ammonia formed and in cell counts 

 the two non-spore-formers had gained the ascendancy. B. cereus was not found although 2.3 

 million per gram were present at the beginning.— The taxonomic study by Conn includes a 

 description of Ps. fluorescens, Ps. aeruginosa, Bacterium termo and Ps. putida with a brief 

 summary of characters of typical Ps. fluorescens and Ps. caudatus. — J. K. Wilson. 



900. Dakin, H. D. On amino acids. Biochem. Jour. 12: 290-317. 1918.— Some new 

 methods are presented for the extraction of amino acids by partially miscible solvents. A 

 new amino acid, hydroxyglutanic acid, and a new peptide from caseinogen, isoleucylvaline, 

 have been isolated and studied. — W. H. Chambers. 



901. Frear, William, Walter Thomas, and H. D. Edmiston. Notes on the use of 

 potassium permanganate in determining nitrogen by the Kjeldahl method. Jour. Assoc. Official 

 Agric. Chem. 3 : 220-224. 1919.— See Bot. Absts. 5, Entry 1005. 



902. Hendrick, Ellwood. Micro-organisms in plant chemistry and nitrogen fixation. 

 An account of the development and application of micro-organisms useful to plant growth — fix- 

 ation of nitrogen in the soil. Chem. and Mettallurg. Eng. 19: 574-576. 6 fig. 1918.— This is 



