330 



SCIENCE 



[N. S. Vol. XXVII. No. 6S7 



by rendering active a proferment. The 

 rate of inversion by equivalent amounts of 

 green and ripe pulp of the same variety 

 are practically identical. Protoplasmic 

 poisons— picric acid, chromic acid and 

 formalin— retard the action of green and 

 ripe pulp, but to approximately the same 

 degree. If the living protoplasm were in 

 any way connected with the inversion, the 

 retardation would be greatly intensified in 

 the presence of protoplasmic poisons. 

 Green date tissue is not rendered inactive 

 by soaking in ether, chloroform, acetone, 

 etc. 



The pi-ess juices of the green date con- 

 tain most of the water in the fruit and 

 large amounts of soluble substances which 

 are usually retained by the healthy and 

 unbroken semipermeable hautschiclit. 

 These juices and extracts are invariably 

 free from invertase until the fruit ripens, 

 although the press residues are always very 

 active. 



Treatment of the tannin-free green date 

 tissue with chloroform, ether, toluol and 

 aceton does not alter the behavior of the 

 invertase towards solvents. Moreover the 

 invertase is not liberated by heat. This 

 treatment should destroy the semiperme- 

 able nature of the protoplasmic wall. 

 From these observations the theory of the 

 impei'meability of the cell wall for the in- 

 vertase of green date is untenable. 



Enzymic action will take place whenever 

 either enzyme or material to be acted upon 

 is soliible; that is, molecular contact must 

 be established. Tannin removes the in- 

 vertase of ripe dates from solution, but in- 

 version is not checked unless the precipitate 

 is filtered off. Date extracts precipitated 

 by lead subaeetate still invert cane sugar, 

 but on removing the precipitate inversion 

 is stopped. It is thus possible to invert 

 sugar by means of invertase artificially 

 rendered insoluble. 



In the place of impermeability of the 



cell wall to the enzyme, the writer proposes 

 the following theory. It is highly probable 

 that green date invertase and possibly 

 other endoenzymes are held in an insoluble 

 combination by some constituent of the 

 protoplasm. In some cases this combina- 

 tion may be broken down and the enzyme 

 pass into solution while the protoplasm is 

 living, but in others the combination may 

 persist even after the death of the proto- 

 plasm. The enzyme may be rendered sol- 

 uble also by external chemical or physical 

 influence. On maturity of the tissues the 

 enzyme is generally liberated, possibly by 

 autodigestion or other profound change in 

 the protoplasm. 



In order to establish the impermeability 

 of the cell wall to the enzyme in any given 

 case it must be shown that the enzyme is 

 in solution in the cell sap and not held in 

 combination by the protoplasm. 

 On the Occurrence of a Phytin-splitting 

 Enzyme in Animal Tissues: E. V. Mc- 

 CoLLUM and E. B. Hart, Chemical 

 Laboratory of the AA^'isconsin Experi- 

 ment Station. 



The authors have examined the influence 

 of blood and of water and glycerine ex- 

 tracts of liver, kidney and muscle upon 

 the sodium salt of anhydroxymethylenedi- 

 phosphoric or phytic acid prepared from 

 wheat bran. The sodium phytate was di- 

 gested at 40° C. for one or two days with 

 blood and with the tissue extracts, and the 

 phosphoric acid in the mixture estimated 

 by the method of Hart and Andrews^ for 

 detennining inorganic phosphoric acid in 

 the presence of phytin. These values were 

 compared with those obtained with blood 

 and the extracts alone. The results indi- 

 cate that blood and the liver of calves pos- 

 sess the power of cleaving sodium phytate 

 with the formation of phosphoric acid. 

 Muscle and kidney as well as the enzymes 

 of the digestive tract do not alter phytin. 

 ' Amer. Chem. Journal, 30, 470 ( 1903 ) . 



