34 Tannin in the Fruit of the Persimmon [Sept. 



in the tannin-mass. Within the Hmits of the size of the cell, how- 

 ever, this associated colloid always occupies the whole space; it 

 takes the form of the "containing vessel." This is shown by ma- 

 terial of both the date {Phoenix, Lloyd, 1910) and the persimmon, 

 which has been preserved by means of copper acetate and with ethyl 

 nitrite vapor. A still more illuminating piece of evidence has been 

 obtained by dropping blocks of hard persimmon mesocarp into boil- 

 ing 20 per cent. cane sugar Solution, and allowing the boiling to con- 

 tinue for two hours. In such material the tannin-cells do not burst, 

 but most, if not all, of the free tannin escapes and combines with the 

 remaining tissues, so that, upon adding ferric chlorid to a section, 

 the whole gives a strong tannin reaction. The tannin-mass, that 

 is, the Compound colloid in question, is now hard, and cuts, with the 

 razor, like hard cheese or coagulated albumin, showing furrows and 

 fractures of the expected kind. Alkaloids produce in it no precip- 

 itate. The material therefore contains no free tannin, is coagulated, 

 and is seen to occupy the whole space of the vacuole. The absence 

 of any internal structure, such as I have already described, indicates 

 that there was some swelling, since swelling, by setting up internal 

 pressures in all directions, is the only way by which the internal 

 structure is eliminated. 



If this view be correct, the change in the tannin cells during 

 ripening consists in an increase in the amount of the colloid. Vin- 

 son's (1910) very interesting experiments on the effects of high 

 temperatures on the fixation of tannin may therefore mean that 

 if the protoplasm is killed, the additional secretion of the associated 

 colloid is prevented. It is quite likely that an enzyme is one factor 

 involved, as Vinson thinks he has proven to be the case. The 

 killing of the protoplasm, releasing " intracellular enzymes," would, 

 however, result in the softening of the fruit. This result would 

 occur, I think, quite independently of the behavior of the tannin. 

 In the Japanese procedure of artificial ripening, appreciable soften- 

 ing of the pulp must not occur, but the tannin must have become 

 fixed. Though other possibilities are not excluded, such as the 

 possible increase in the tannin itself during some stages of ripening, 

 I think it probable that the successful processing of persimmons 

 consists in an Operation during which the increase of the associated 



