[LLOYD] TANNIN IN THE LIVING CELL 11 



body is more than doubtful, in Spirogyra at all events, in the light of 

 van Wisselingh's studies; but that sugars or other substances may 

 function in this sense remains possible. 



It seems unlikely that tannin is always a protoplasmic poison 

 for all plants. But admitting this to be the case it is not precluded 

 from functioning in the metabolism of the plant. It seems rather 

 more probable that in some cases tannin is toxic and in others not, 

 and that the chemical structure correspondingly differs. In the 

 former event the presence of a strongly adsorbing body is explicable; 

 if the latter is the case its absence would need no explanation; weakly 

 adsorbing bodies then permit its ready use. 



As to the functions of tannin, I may first say that the plural has 

 been used advisedly. It seems as true that some tannin is quite 

 useless, and is merely a by-product, as that other tannin is useful. 

 There is fairly conclusive evidence that tannin enters into the carbo- 

 hydrate economy of the plant, but to say that the tannin in the peri- 

 carp could not be useful were it more fortunately situated, as one may 

 say, may be as gratuitous as to assert the same of the sugar in a 

 banana. Here, it is evidently a waste, but not a useless product! 

 With Dekker we must incline to think that the usefulness of tannin 

 lies not in serving one function alone. The effort to find a single 

 function has probably impeded the progress of our search. 



LITERATURE CITED 



1892. Baccarini, P. Contributo alia conoscenza dell'apparecchio 



albuminoso-tannico delle Leguminose. Malpighia 6: 1-99 pi. 



21-26. 

 1913. Clark, E. D. Notes on the chemical nature of the "tannin 



masses" in the fruit of the persimmon. Biochem. Bull. ^:412- 



418. Ap. 

 1911. Cook, Mel. T. and Taubenhaus, J. J. Relation of parasitic 



fungi to the cell contents of the host plant. I. The Toxicity 



of Tannin. Del. Ag. Exp. Sta. Bull. 91. 

 1915. Cook, Mel. T. and Wilson, G. W. The influence of the 



tannin content of the host plant on Endothia parasitica and 



related species. Bot. Gaz. 60: 346-361. Nov. 

 1911. CzAPEK, Fr. Ueber eine Méthode zur direkten Bestimmung 



der oberflaechenspannung der Plasmahaut von Pflanzenzellen. 



Jena, 1911. 

 1882. Darwin, Charles. The action of carbonate of ammonia on 



the roots of certain plants. Jour. Linn. Soc. 19: 239. 



