22 Tannin in the Fruit of the Persimmon [Sept. 



change from a fluid condition to one of relative immobility, the 

 amount of free, or "soluble" tannin decreases. The behavior of 

 this under the special conditions of investigation, as well as in the 

 fruit, will now be described. It will make for an easier under- 

 standing of the facts if it be made piain at once that there is 

 always some free tannin, no matter how far advanced in ripening 

 the fruit may be. Indeed, Bigelow, Gore and Howard (1906, table 

 II) reported finding traces of tannin in all their analyses. This 

 is not explained by them, and might very well be thought to be of 

 no significance from a chemical point of view. From the present 

 one, however, the fact is of importance. To show that free tannin 

 is always present, I have examined freshly made filtrates of dozens 

 of fruits, in all stages from incipient ripening to complete disinte- 

 gration. In order to eliminate the possibility of tannin-extraction 

 by fungi, I have kept fruits in Chloroform vapor and with thymol. 

 If a fruit be allowed to stand on a plate, it will in time pass into a 

 condition when the skin breaks and the fluids ooze out, free from 

 the cells. This fluid contains a readily demonstrable amount of 

 tannin. As an extreme example, I find free tannin also in the fruit 

 already mentioned which, after treatment for three days with acetic 

 acid, has stood for three months. I think we may conclude that, 

 aside from fruits which have been treated with substances which 

 unite chemically with tannin, there is always a small amount of 

 tannin which fails to become fixed and is there fore non-astringent. 

 The amount may be too small to be detected through its action on 

 mucous membranes.^^ 



From its fluid condition in the hard fruit, the tannin-mass 

 passes, always gradually of course, into one of semi-coagulation. 

 When in this condition, upon the addition of water to the prep- 

 aration, the cell bursts, the tannin-mass breaks out in irregulär 

 fashion (fig. 6c). Its behavior suggests that of the albumin of 

 an tgg after being cooked by the method which produces "cod- 

 dling." Upon extrusion, a cloud of free tannin is seen to Sur- 

 round it so rapidly that one has the same difficulty in ascertaining 

 its origin as when the tannin-mass is quite fluid. It is, however, 

 clear to the observer that the tannin-mass retains whatever shape 



" I am indebted to Mr. H. P. Bassett for pointing out that this tannin may 

 be of the kind (iron-green) which does not combine with albumin, pectose, etc. 



