1916] AGRICULTURAL CHEMISTRY — AGROTECHNT. 313 



pounds and owing to its firm combination with the lignin of the cell walls is 

 only separated with difficulty and would not easily pass into the juice." 



Studies on the relation of cement dust to citrus veg'etation. — I, The effect 

 on photosynthesis, H. D, Young {Biochem. Bui., 5 {1916), No. 18-19, pp. 95- 

 100). — The investigation has shown that the coating of dust on orange leaves 

 adjacent to cement plants amounted in many cases to as much as 0.0034 gm. 

 per square centimeter and corresponded in composition very closely to the 

 " raw mixture " from which the cement was made. The amount of dust found 

 on such leaves may shut out as much as 80 per cent of light from the upper 

 surface of the leaf. This exclusion of light, however, does not interfere with 

 the carbohydrate synthesis. The metabolic activity of new leaves was only 

 slightly greater than that of old leaves. 



Researches on arg'inase; concerning the action of arg'inase on creatin, 

 A. Cr.EMENTi (Atti R. Acad. Lincei, Rend. CI. Sci. Fis., Mat. c Nat., 5. ser., 

 24 {1915), I, No. 5, pp. 483-489).— It has been demonstrated that creatin is not 

 hydrolyzed into urea and sarcosin by arginase, thus confirming the previous 

 finding of Dakin." Arginase is not a ferment capable of detaching the guanidin 

 nucleus from any compound to which it may be bound, as would be indicated 

 by the name " deguanidase," which has recently been proposed. The inability 

 of arginase to hydrolyze creatin supports the contention of the specificity of 

 the enzym. 



Adsorption of invertase, J. M. Nelson and E. C. Griffin {Jour. Amer. Chem. 

 Soc, 38 {1916), No. 5, pp. 1109-1115).— From the investigation it is concluded 

 •' that invertase is colloidal in nature, and the reaction between the enzym and 

 cane-sugar solution depends on the contact of two phases. The activity of 

 invertase ... is not affected whether or not the enzym is adsorbed to a solid 

 like charcoal, or to a colloid like saponin, serum, or egg albumin, distributed 

 uniformly throughout the solution of the substrate. Displacing the adsorbed 

 invertase by a second colloid is without effect on the activity, contrary to the 

 views held by many. Invertase can be removed from an aqueous solution by 

 adsorption to a solid, and again brought into solution by a second colloid sus- 

 pended uniformly throughout the solution. Eriksson's proof that cane sugar 

 can liberate invertase adsorbed to charcoal is not valid." 



The experimental methods used were those described in the communication 

 previously noted (E. S. R., 34, p. 803). 



The occurrence of urease in hig'her plants, M. W. Beijerinck {Chem. 

 WeekU., IS {1916), No. 16, pp. 443, 444). — The author has found urease in the 

 cortex of W.\e twigs and in the buds of Glycine sinensis and Cytisus lahurnum. 

 The seeds of the latter were especially rich in urease, although considerably 

 less was found than is present in the soy bean. Its presence was also demon- 

 strated in the bark of the ordinary acacia, Robinia pseudacacia, in the seeds 

 of the indigo plant, and in the tissues of the various herbaceous Papilionaceae. 

 Its presence could not be determined in peas, beans, flaxseed, almonds, and 

 various other plants examined. 



A simple device for reg'ulating- the pump used in exhausting a vacuum 

 oven, G. P. Plaisance and D. V. Moses {Jour. Amer. Chem. Soc., 38 {1916), 

 No. 5, pp. 1063-1065, fig. 1). — The authors describe in detail a simple automatic 

 device for maintaining any desired pressure in a Freas electrically heated 

 vacuum oven. The apparatus is easily assembled and has given entire satis- 

 faction. 



A new form of gas burette, Hammermann {Chem. Ztg., 40 {1916), No. 10-11, 

 p. 84, fig. 1). — An apparatus to measure gases only .slightly soluble in water, in 



'Jour. Biol. Chem., 3 (1907), No. 5, pp. 435-441, 



