i8 Tannin in the Fruit of the Persimmon [Sept. 



appears as a colored granulär precipitate, while the latter is a 

 homogeneous mass of the same color, the color corresponding to 

 the reagent used. Only one explanation of this has occurred to me, 

 namely, that the tannin of the intact cell is all held within the con- 

 fines of a colloidal Compound which gives the form and body to 

 the tannin-mass, but that upon swelling, followed by the bursting 

 of the cell, so much tannin as is not firmly held chemically as a 

 part of the colloidal Compound, escapes by expression and diffusion 

 into the surrounding fluid. 



I wish to emphasize the importance of the observations on 

 which this explanation is based. The bursting of a tannin-cell of 

 a hard unripe fruit is followed by the outflow of a stream of color- 

 less fluid, which mingles with the water. If, as the stream flows, 

 a reagent, such as ferric acetate, be added, the stream may be dif- 

 ferentiated into two parts, an outer sheath of precipitate and an 

 inner core of mucilaginous matter (flg. 6c). The core may be ob- 

 served to move forwards independently or, if the pressure of the 

 Cover be changed, backwards (fig. 6a-b). Both react by the proper 

 change of color. Careful study will show that the precipitate 

 (free tannin combined with the reagent and, possibly, with an- 

 other substance) originates hy diffusion froin the mucilaginous core. 

 The material of this core at length gives up no more free tannin, 

 but itself still reacts, showing that it contains " insoluble tannin." 

 It would seem therefore that the intact cell is filled with a colloid 

 Solution which contains a large proportion of water. The tannin 

 is in part combined with the colloid and in part in Solution in the 

 water in the interstices of the colloid. If this be the case, one would 

 expect that free tannin could be demonstrated within the cell, as, 

 for example, by causing the tannin-mass to shrink. The difficulties 

 of Observation, however are great. It is impossible to get a prep- 

 aration of a tannin-cell without the fruit-juice carrying the spilled 

 Contents of other tannin-cells. Washing or applying a watery rea- 

 gent, causes bursting. With glycerol, combined with a very little 

 ferric acetate, shrinkage occurs, but unequivocal evidence of the 

 extrusion of free tannin has not been observed. It would rather 

 seem that, so long as the tannin-mass shrinks, the free tannin is 

 held imprisoned, as above described. 



