124 



GIBBS. 



appearance. Simultaneously with the formation of this precipitate the 

 inversion of the sucrose begins. 



Inversion. — ^The inversion proceeds in practically the same manner in 

 all the palm saps investigated and is undoubtedly due to the formation of 

 an invertase, which appears as a precipitate, from a z5Tnogen which exists 

 in solution in the sap. 



The invertase develops, probably under the influence of the atmos- 

 phere, after the sap has exuded from the cut stem. The acti-^dty of the 

 white precipitate which is not soluble in the sucrose solution corresponds 

 in a measure to the conditions found by A'inson ^® in the fruit of the 

 date palm. He identified an insoluble invertase from the cellular struc- 

 ture. In the case of the palm saps an insoluble invertase is precipitated 

 from a clear solution containing no invertase. The chemical composition 

 of the four palm saps investigated is practically identical and the beha- 

 vior of the invertase from each shows no observed differences worthy of 

 note. 



A sample from tree number 5 (see table of analyses) was allowed 

 to stand in the glass bottle in which it was collected, and polarized at 

 various intervals. 



Table VII. — Spontaneous inversion of the sap of one tree, collected in a glass 

 vessel {measurements at atmospheric temperature from 24° to 30°). 



Date. 



Hour. 



Time 

 interval. 



Reading 

 in a 10- 

 centi- 

 meter 

 tube. 



Per cent 

 of inver- 

 sion, 

 approxi- 

 mate. 



December 14 



3. p.m 



4.15 p. m 



7.20 p.m 



8.55 p.m 



10.30 p. m 



8.30 a. m 



10.30 a. m 



ft. m. 



10 



1 15 



4 20 



5 55 

 7 30 



17 30 

 43 30 



28.8 

 28.8 

 28.8 

 27.6 

 26.5 

 23.0 

 1.8 



0.0 

 0.0 

 0.0 

 4.2 

 8.0 

 20.1 

 93.7 



Do. -- 



Do 



Do 



December 15 



December 16 



Samples which are not collected in clean vessels do not show the initial 

 stable period of four or five hours. At 7.15 on the morning of November 

 21, 1910, fifteen plant stems were washed to free them from molds and 

 other organisms as much as possible, and the bamboo collecting vessels 

 washed clean and placed in position. The sap was allowed to flow forty- 



^"Bot. Gaz. (1907), 43, 393. Journ. Amer. Chem. Soc. (1908), 30, 1005: 

 Jourr(. Biol. Chem. (1910), 7, proceedings XX. 



