204 EXPERIMENT STATION RECORD. [Vol.35 



"Enzymic activity is thus manifested at the interface of contact between 

 the solid enzym phase and the liquid substrate phase. The catalysts concerned 

 are not in true solution." 



I, The relation of hydrogen ion concentration of media to the proteolytic 

 activity of Bacillus subtilis. II, Proteolysis of Streptococcus erysipelatis 

 and S. lacticus compared under different hydrogen ion concentration, A. 

 ITANO (Massachusetts Sta. Bui. 161 (1916), pp. 139-185, figs. 6).— The bac- 

 teriological value of Sorensen's method for the study of proteolysis in conjunc- 

 tion with variations in the hydrogen ion concentration has been determined, the 

 organism B. subtilis being used in the investigation. It was shown that cer- 

 tain hydrogen ion concentrations measure the exact influence, both inhibitory 

 and prohibitory, and indicate the exact limits of the proteolytic activity of 

 the micro-organism. With increasing proteolysis the hydrogen ion concentration 

 of the medium converges toward the optimum. The results indicate that B. 

 subtilis produces endoenzym and no exoenzym. Sorensen's method yielded very 

 satisfactory results in determining the rate of proteolysis. For obtaining any 

 desired hydrogen ion concentration in a medium the colorimetric method was 

 used. 



The apparatus and technique employed in the investigation are described in 

 detail. A review of the earlier literature on the subject is also included. 



Part 2 deals with the application of the method developed in the investiga- 

 tion to a study of S. erysipelatis and S. lacticus. The virulent strain of S. ery- 

 sipelatis was found to multiply much more rapidly in a broth medium than the 

 nonvirulent strain, S. lacticus. A difference both in degree and rate of proteo- 

 lysis was evident, S. erysipelatis being much more active and vigorous. The 

 results indicate a very close relationship between the optimum hydrogen ion 

 concentration for proteolysis (in the bouillon) and the hydrogen ion concentra- 

 tion of the natural environment of the organisms (blood and milk). 



The general applicability of the paper pulp filter to quantitative analysis, 

 S. L. JoDiDi and E. H. Kellogg (Jour. Indus, and Engin. Chem., 8 (1916), No. 4> 

 pp. 317-319). — Experimental data submitted indicate that the application of the 

 pulp filter to the quantitative estimation of barium and sulphuric acid as barium 

 sulphate, of silver and hydrochloric acid as silver chlorid, and of potassium 

 and ammonium as chloroplatinate gives results as accurate as those obtained by 

 the use of standard filter paper. See also a previous note (E. S. R., 34, p. 712). 



A simple apparatus for filtration under diminished pressure, J. C. Irvine 

 (Biochcm. Jour., 9 (1915), No. 3, pp. 321, 322, fig. 1). — An apparatus is de- 

 scribed in which a specially designed cylindrical tube is used instead of an 

 ordinary suction flasli for filtration under diminished pressure. The apparatus 

 is deemed of special value when manipulating small quantities of material in 

 that it obviates undue loss in transferring the material to another container. 



Color standards and colorimetric assays, H. V. Akny and C. H. Ring (Jour. 

 Indus, and Engin. CTiem., 8 (1916), No. 4, pp. 309-311). — The preparation of 

 color standards for ammonia, nitrate, nitrite, vanillin, uric-acid, salicylic-acid, 

 and phosphate colorimetric procedures is described in detail. The solutions 

 used for making standard blends are divided into three series, viz, cobalt-iron- 

 copper, cobalt-chromium-copper, and chromium-manganate. 



Some indicators from animal tissues, W. J. Ckoziee (Jour. Biol. CJiem., 24 

 (1916), No. 4, pp. 443-445). — The preparation and color changes of indicators 

 prepared from Ascidia atra, PtycJiodera sp., Cliromodoris zebra, and Eupolymnia 

 aurantiaca (?) are reported. 



The influence of fluorspar on the solubility of basic slag in citric acid, 

 G. S. RoBEKTSON (Jour. Soc. Chem. Indus., 35 (1916), No. 4, pp. 216, 211).— 

 Experimental data submitted indicate that the citric-acid test gives no true 



