108 EXPERIMENT STATION EECORD. 



lieating upon the peptic and tryptic digestion in vitro of white of egg, gelatin, 

 fibrin, beef, and casein. The number of cubic centimeters of sodium hydrate 

 required to neutralize the digestion mixture increases clearly after the thir- 

 teenth day of peptic digestion of ovalbumin and gelatin ; also in the eighth day 

 of beef; and after the second day digestion of casein and fibrin. 



" The above results, as could be foreseen, gave no clear conclusions about the 

 digestive activity of pepsin, but they decisively bear out the view of the slow 

 liberation of amino-acids groupings by this enzym. Preliminary heating of egg 

 white at 120 to 140° C. makes trypsin proteolysis more active. Preliminary, 

 heating increases the tryptic digestion of fibrin, casein, and beef, and decreases 

 that of gelatin. The amino-acids groupings in tryptic solutions increase after 

 15 hours' digestion." 



The kinetics of invertase action, L. Michaels and Miss M. L. Menten 

 {Bvochem. Ztschr., Jf9 (1913), No. 5, pp. 333-369, figs. i9).— Saccharose appar- 

 ently combines with invertase to form a compound with a dissociation constant 

 of 0.0167. The combination is labile according to the equation 1 molecule sac- 

 charose-invertase compound — >1 molecule fi'uctose+1 molecule glucose+1 mole- 

 cule invertase. Invertase also has an affiinity for fructose, glucose, the higher 

 alcohols (mannit, glycerol), and other carbohydrates, but not for lactose. The 

 affinity, however, is smaller than for saccharose and the compound is not labile. 



The concentration of all the compounds can be calculated from the law of 

 mass action, and fairly accurate dissociation constants can therefore be easily 

 supplied for each. The most exact dissociation constant is for the saccharose- 

 invertase compound. As the decomposition of the saccharose-invertase com- 

 pound must be a monomolecular reaction, the rate of decomposition of the 

 saccharose is proportional to the concentration of the saccharose-invertase 

 compound. 



The localization of betain in plants, V. Stanek (Ztschr. Zuckerindus. 

 Bohmen, 37 (1913), No. 8, pp. 385-390; ahs. in Chem. Ztg., 37 (1913), No. 65, 

 Repert., p. 296). — The data show that betain Is very unevenly distributed in 

 plants, but is chiefly present in young leaves and shoots which are still green. 

 Probably this substance plays a part in the nitrogen economy of the plant. 

 Seeds do not contain betain as a reserve material. 



Studies in the chemistry and physiology of the leaves of the betel vine 

 (Piper betle), and of the commercial bleaching of betel-vine leaves, H. H. 

 Mann, D. L. Sahasrabuddhe, and V. G. Patwardhan (Mem. Dept. Agr. India, 

 Chem. Set'., 3 (1913), No. 2, pp. 17-63). — An investigation of certain aspects of 

 the chemistry and physiology of this plant, which is reported under the follow- 

 ing heads: "(1) The occurrence of nitrates in betel-vine leaves and plants, and 

 their relationship to the growth of their vine; (2) the sugars, starch, tannin, 

 essential oil, and other normal constituents of the betel vine and their relation- 

 ship to the growth of the vine; (3) the commercial bleaching of the betel-vine 

 leaf, and the chemical changes by which it is accompanied." 



Chemical studies on the lime-sulphur-lead arsenate spray mixture, W. E. 

 Ruth (Jour. Indus, and Engin. Chem., 5 (1913), No. 10, pp. 847-850). — Pre- 

 viously noted from another source (E. S. R, 29, p. 802). 



The titrimetric determination of ammonia, L. W. Winkler (ZUchr. Angew. 

 Chem., 26 (1913), No. 31, AufsatztcU, pp. 231, 232; abs. in Chem. Ztg., 37 (1913), 

 No. 65, Repert., p. 293). — Instead of either hydrochloric acid or sulphuric acid 

 solutions, boric acid (3 gm. of crystallized boric acid in 100 cc. of water) in 

 excess can he employed to collect the ammonia on distillation. As boric acid 

 reacts neutrally towai'd Congo red and methyl orange, the excess of boric acid 

 present can be titrated with standard hydrochloric acid solution. 



