812 EXPERIMENT STATION RECORD. [Vol. 37 



this joiut taper slightly into each other so as to come together and take up any 

 looseness resulting from wear. The cleaning tube has an outside diameter 

 that permits it to slip easily but snugly through the surface shield. 



The use of the sampler is also described. 



The influence of available carbohydrates upon ammonia accumulation by 

 microorganisms, S. A. Waksman {Jour. Ajuer. Chcm. Soc, S9 (1911), No. 7, 

 pp. 1503-1512). — Experiments conducted at the University of California on the 

 influence of carbohydrates on ammonia and amino nitrogen accumulations by 

 soil microorganisms are reported. The organisms studied were Aspergillus 

 niger and Citromyces glabcr, isolated from soil by the author. 



It was found that " the effect of sugar on the accumulation of ammonia by 

 A. niger is marked. Where the sugar was absent the organism made a rather 

 slow growth, as shown by the weight of the mycelium, but the ammonia ac- 

 cumulated in large quantities from the third till the sixteenth day, the amount 

 increasing rapidly, so tliat on the sixteenth day about a half of the total nitro- 

 gen of the medium was in the form of ammonia. Where the sugar was present 

 the ammonia accumulated only In very small quantities, while the weight of 

 the mycelium increased rapidly until the seventh day, when autolysis set in 

 and the weight of the fungus body began to decrease. The amount of ammonia 

 accumulated was small when the organism grow rapidly ; but as the maximum 

 of growth was reached, whidi was also accompanied by the utilization of all 

 the sugar in the medium, the ammonia l>egan to accumulate very rapidly." 



The same results were obtained with C. glabcr, the excess of sugar corre- 

 sponding to a decrease in the amount of ammonia pre.<;ent in the medium. " In 

 the production of amino nitrogen C. plabcr behaves in an entirely different 

 manner from A. niger; It was found that many organisms which are not able 

 to reduce the proteins to ammonia, whether in the presence or absence of avail- 

 able carbohydrates, may split the proteins Into amino acids which accumulate 

 In the medium. 



" This experiment shows again that, when available carbohydrates are pres- 

 ent, the organism will utilize all the nitrogen split off from the protein for its 

 own metabolism; while in the absence of available carbohydrates, or where 

 these have been used up. the protein molecule will be attacked not only for Its 

 nitrogen content hut also for Its carbon content." 



Effect of paraffin on the accumulation of ammonia and nitrates in the soil, 

 P. L. Gainey {U. S. Dcpt. Agr., Jour. Agr. Rciearch. 10 (1917), No. 7, pp. S55- 

 S64). — In experiments at the Kansas Experiment Station paraflin and Parowax 

 In thin shaving.^ and paraflin oil were added to a soil having a vigorous ammonia 

 and nitrate-forming flora at the rate of 2 gm. per 100 gm. of soil. In certain 

 cases also the insides of the 500-cc. bottles used in the Incubation test were 

 paraffined or parowaxed. In certain cases no additions were made of nitrogen 

 or calcium carbonate. In other cases nitrogen was added in the form of cotton- 

 seed meal and ammonium sulphate at rates of ,^0 mg.. and calcium carbonate at 

 the rate of 0.5 gm. per TOO gm. of soil. 



In the tests in which no nitrogen was added, and regardless of whether cal- 

 cium carbonate was added, paraffin In the three forms used not only inhibited 

 the accumulation of ammonia and nitrate nitrogen, but caused that which was 

 present at the beginning of the experiments to disappear. This effect was 

 maintained for 13 weeks and even longer, and regardless of whether the paraffin 

 was intimately mixed with the soil or simply lined the Inner wall of the con- 

 tainer. 



