108 FRANCIS E. LLOYD 



capacity for hydratation, any access of water to the tannin-cells, 

 before coagulation is complete, causes the X-cellulose to swell suf- 

 ficiently to burst the cell wall. After death of the cell, and when 

 syneresis has advanced, the volume occupied by the X-cellulose 

 is much less than previously, and its capacity for swelling is 

 very limited and always insufficient to cause rupture of the cell 

 wall. 



Associated with the X-cellulose is the tannin. This, during 

 the unripe stages, is loosely adsorbed by the X-cellulose so that 

 upon hydratation of the latter sufficient to break through the 

 cell wall, the tannin partly escapes into the surrounding water. 

 As ripening becomes more advanced, the coagulation of the 

 X-cellulose becomes more pronounced, and the adsorption of the 

 tannin more complete. The amount which may then escape 

 upon increased hydratation of the X-cellulose becomes less and 

 less until it is too small to be appreciable. There is, of course, 

 no such condition as complete non-astringency, except in a 

 merely gustatory sense, for tannin diffuses out of the even com- 

 pletely coagulated tannin-masses, but only very slowly. In this 

 connection it may be pointed out that the earlier conception of 

 ''soluble" and "insoluble" tannin is inadequate. The fruit is 

 then non-astringent. If the fruit is kept for some time, the 

 tannin becomes oxidized and red in colour when the tannin- 

 masses (the masses of coagulated X-cellulose and adsorbed tan- 

 nin) can be readily recognized. Syneresis, too, becomes pro- 

 nounced. 



Meanwhile, the hydrolysis of the intercellular substances has 

 proceeded, together with changes in the content of sugar and other 

 substances,^ in part consequence of which the fruit becomes soft- 

 ened, even, at length, to wateriness. The tannin cells are then 

 quite free from each other and from their neighbouring paren- 

 chyma cells, and these, inter se, equally so. The various 

 changes do not, however, proceed in all fruits at the same relative 

 rates, for some fruits become non-astringent before softening, 

 others only after an advanced stage of softening has been reached. 



* Bigelow, Gore and Howard. Journ. Amer. Chem. Soc, 28: 688, 1906. 



