I819] SOILS — FERTILIZERS. 721 



silty clay loam soil underlain with limestone rock to ascertain whether evapo- 

 ration on the strain bath occasions changes that affect the acidity as determined 

 by the Veltch method (B. 8. it., L6, i>. 14). Soil samples were taken at different 

 depths and in different places in the field, air dried, arid all material except that 

 of a stony nature reduced to pass through a 1-min. sie\e. The samples were 

 then tested by the Hopkins potassium nitrate method and by the Veit'-h method, 

 using [10 lime water, with and without evaporation on the steam hath. 



The results are held to show that "there are reactions taking place in the 

 soil at the steam bath temperature that do not take place when the soil and 

 water mixture is not heated. The Witch determination gives the reactions 

 between soil, water, and calcium hydmxid ai steam hath temperature, and does 

 not represent the lime requirement of the soil at ordinary temperature." 



Studies on proteolytic activities of soil microorganisms, with special ref- 

 erence to fungi, S. A. Waksman (./our. Bad., 3 (1018), No. 5, pp. £75-492, figs. 

 2; als. in Chi in. 4.6*., 13 (1010), No. ■'>. p. J/80). — Aspergillus niger, A. ochraceus, 

 A. fusous, A. clavatus, Citromyces <ji<ii><r, Penicillium chryaogenwn, Actinomi 

 penicilloidet n. sp., .1. violaceus-ruber, A. diastaticus, and Bacterium mycoides 

 were grown on C/apek's solution and in media in which peptone or casein 

 replaced sodium nitrate or both the nitrate and cane sugar. Cultures were 

 also made in which the nitrate was replaced by 1, 5, 10, and 23 gm. ot asparagin 

 per liter of Czapek's solution. 



It was found that "different organisms behave differently in their power to 

 attack proteins and in the production of amino nitrogen and ammonia. Most 

 of the molds which grow very rapidly, as manifested hy the increase in weight 

 of their mycelium, allow a small amount of amino nitrogen to accumulate in the 

 medium, while the amount of ammonia accumulated increases with the period 

 of Incubation. Certain molds, particularly the slower growing ones, the 

 actlnomyces studied, and li. mycoides favor a large accumulation of amino 

 nitrogen in the medium and a comparatively smaller accumulation of am- 

 monia. The growth of A. nif/cr upon a solution containing peptone shows that 

 the amino nitrogen produced in the medium is used up by the organism, so 

 that no great accumulation takes place. Ammonia, on the other hand, which 

 seems to be a waste product of the metabolism of the organism, accumulates 

 readily in the medium, particularly when the organism stops growing and 

 begins to autolize. The presence of available carhohydrates checks the accu- 

 mulation of ammonia in the medium, due to the fact that in their presence the 

 organism uses only as much of the protein molecule as it needs for its nitrogen 

 metabolism, and only a small quantity of ammonia will accumulate. The process 

 of ammonificatlon, in the presence of availahle carbohyd rates, is found to be 

 an autocatalytic chemical reaction. In the absence of available carbohydrates 

 the observed data deviated from the data calculated hy the use of the curve 

 of autocatalysis. 



"The study of ammonification is of doubtful importance In revealing to us 

 the proteolytic activities of microorganisms, since the quantity of ammonia 

 accumulated in the medium depends on a great number of controlling factors; 

 it has not been proven as yet that ammonia is an end product of protein 

 metabolism. 



"Asparagin nitrogen is rapidly converted into ammonia nitrogen, after the 

 organism ha-s made its maximum growth; but, where the amount of asparagin 

 nitrogen is small, particularly in the presence of a comparatively large exeo-s 

 of available carhohydrates, no ammonia or only a very small quantity of it 

 will accumulate in the medium." 

 120053°— 19 3 



