Tannin in Persimmons. 9 



ripening, or softening, period by boiling for a sufficiently long 

 time with changes of water, but can not be extracted with either 

 water or alcohol after a point of change is reached some time 

 previous to that when rupturing of the cell may still take place. 

 It would seem that there occurs a brief period when the quanti- 

 tative relations of the tannin and hypothetical carrier are such 

 as to imprison the whole of the tannin. It may very well be 

 that the loss of fluidity is due to a complete union of the two 

 substances, and that the physical characters of the mass there- 

 after are peculiar to the compound. 



The underlving causes for the remarkable change have been 

 sought for by Vinson (1910). The great variety of chemical 

 agents tried by him to hasten its progress appears to discount the 

 idea that there is a chemical process * involving the tannin 

 itself which renders it insoluble. Heat was found to effect the 

 same results, but within the limits usually indicative of enzy- 

 motic activity, $ and of the cessation of direct protoplasmatic 

 activity. There is nothing in this conclusion, important as it 

 is, to excite wonder. From my observations of the ripening 

 process in persimmons, I am almost of the mind that the death 

 of the protoplasm ensues under normal conditions, at about the 

 time of digestion of the middle lamella, which, as above stated, 

 leads to a final plasmolysis of the cells of the mesocarp. Indeed 

 the secretion of a supposed ferment which may excite the 

 changes in the tannin-cells may be a death character. 



As to the possibility of tasting the tannin, it is true that if 

 the pulp is soft, so that a portion may be taken into the mouth 

 without breaking the tannin-cells, the astringency will ensue, 

 as Howard says, only upon their bursting, for obvious reasons. 

 But I think that it is shown that the bursting of these cells is not 

 necessarily followed by detectable astringency, since the tannin 

 may have become wholly insoluble. 



In the ultimate condition of dehydration, the tannin-mass 

 is sufficiently dense so that it fragments with but a little pres- 

 sure, but not before it has shown at least a slight resiliency. 

 Coincident with the progressive change toward this state the 

 mass shrinks and becomes either angular (Howard) or lobate. 



*The color reactions must be taken into account. These may, however, be subsequent 

 to insohibility. 



i I may here recall the fact that dehydration and other changes proceed in the digestive 

 tract and in the test tube with pep.sin. 



