i92o] CURREXT LITERATURE 191 



times unity, but with higher concentrations it becomes considerably less than 

 unity. Although this relation can be expressed by the adsorption formula 

 y=kc m (y is the final internal, c the final external concentration, and k and m 

 are constants), the writers do not feel the data justify the conclusion that 

 absorption of these salts is an adsorption phenomenon. 



Rations are absorbed initially in the order K, [Ca, Na], Li, [Mg, Zn], Al; 

 as equilibrium is approached the order is K, Na, Li, [Ca, Mg]. The initial 

 order for the anions is S0 4 , N0 3 , CI; the final order, N0 3 , CI, S0 4 . "Although 

 Troendle's view, that in any group of the periodic classification the metallic 

 ions are absorbed more rapidly the higher the atomic weight, is not contra- 

 dicted, yet the view that the initial rate of absorption is largely dependent 

 upon the mobility of the ions or diffusibility of the salt is equally well supported, 

 and can be put forward provisionally as a more reasonable hypothesis." 



Another paper, by Stiles and Jorgensen, 2 * is polemical with Thoday, 

 concerning the method of estimating the osmotic pressure of sap by the swelling 

 or shrinkage of the tissue w T hen immersed in salt solutions. Using sections of 

 the root of the red beet, they found that they neither gained nor lost in weight 

 in 0,40 N NaCl, and that this concentration was qlso just insufficient to cause 

 plasmolysis. The writers therefore maintain that this concentration is 

 approximately isotonic with the beet root sap. — J. J. Willaman. 



Tyrosin in fungi. — Dodge 23 reports some investigations on the chemistry 

 of the tyrosinase reaction in the fungi which turn blue or black on exposure 

 to air. The fungi were sliced, dried, and then ground into a flour, and this 

 fungus flour used in the investigation. "In the work with tyrosin, the dried 

 fungus flour w-as added directly to the substrate, toluol added, and the mixture 

 left to extract the enzym and the enzym to react with the tyrosin." The 

 author studied the reactions with the amino, carboxyl, and phenol groups. A 

 modified form of the "micro" Van Slyke apparatus was used for the determi- 

 nation of the amino nitrogen, the permutite method of Folix and Bell for 

 the determination of ammonia, and the colorimeter method of Duggar and 

 Dodge for the determination of the carboxyl and phenol groups. 



The following conclusions are drawn from these investigations: "(1) that 

 the tyrosinase reaction is not a deamination, although it is possible that 

 deaminases may exist in the same organism with tyrosinase; (2) that the 

 tyrosin molecule is synthesized into a larger, more complex molecule, in which 

 part of the carboxyl groups is either split off as carbon dioxide, or more proba- 

 bly bound in the molecule so that it will not react with alkali."— J. Woodard. 



22 



W., and Jorgensen, W., On the relation of plasmolysis to the shrinkage 



of plant tissue in salt solutions. New Phytol. 18:40-50. 1919. 



2 * Dodge, C. W., Tyrosin in the fungi: chemistry and methods of studying the 

 tyrosinase reaction. Ann. Mo. Bot. Gard. 6:71-92. 1919. 



