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ME. S. LE M. MOORE S STUDIES 



















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such ready yielders of that important translocation-product glucose, 

 are entirely excrementitious ; others hold them to be themselves 

 translocation-products ; while a middle course is steered by yet 

 others, who think that both functions, assimilative and excretory, 

 are performed by these bodies. An antiseptic role has also been 

 ascribed to tannin, and, on account of its bitterness, it has been 

 supposed to protect plants against the depredations of animals. 



I cannot help thinking that it is rash to argue, because direct 

 participation of tannin in metabolism is not discoverable, that 

 therefore it is an excretory substance. An important part may 

 possibly be taken by it in the lignification of cell-walls ; but it 

 will not be necessary to treat of this matter except to refer to the 

 apparent presence of glucosides in lignified cell-walls *. In tannin 

 we have a glucoside which is present often in great quantities 

 in the plant tissues : it undoubtedly moves from one part to an- 

 other, and its production depends upon conditions favourable to 

 metabolism. On the other hand, it cannot be distinctly shown 

 to participate in metabolism. What, then, can have become of 

 it ? Is the glucoside in lignin formed afresh when there is already 

 plenty of tannin in the plant ? And even with regard to the 

 iron-greening tannin, which we have seen reason to believe is 

 largely excreted from the surface of plants f , and which is doubt- 

 less primarily a waste product, it must be remembered, since 

 NageliJ has found that tannin can function as the source of 

 carbon to fungi, that the metabolism of fungi may perhaps involve 

 katabolism of quasi-useless bodies, such as tannin, and pro- 

 duction of substances capable of being used up in the nutrition 

 of higher vegetation. 









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JBusgen (Jen. Zeitschr. f. Naturwiss. 1889) [Prote 

 if any, in constructive metabolism not yet proven]. 



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given 













t The storing up, by the temporary hairs ofglabrate organs, of tannin formed 

 in the meristem may also be a means whereby the plant is enabled to rid itself 

 of the glucoside. The hairs of the Ivy, for instance, are large and can contain 

 a relatively great quantity of tannin, and they soon drop off. But Schenk (' Ver- 

 gleichende Anatomie der submersen Gewachse,' quoted by Stahl in Jen. Zeitschr. 

 f. Naturwiss. 1888, p. 594) regards the caducous tannin-filled hairs of Cerato- 



m as a special protection for the young organs. 



X Sitzb. der k. bayer. Akad. der Wiss. 1880. d. 339. 









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See also Van Tieghem, 











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