( 687 ) 
terial in the resting periods of vegetation, tannin generally belongs, 
according to Wigand, to the tluid active substances necessary for 
growth. In some cases it appears, according to the same author, to 
act as reserve material. It thus follows that in Wigand’s opinion 
tannin is an extremely important product of vegetable metabolism. 
No other investigator has declared this so clearly and so emphatically. 
Wigand’s view has been attacked, especially by Sachs, and has 
not received much support from botanists in general; this is evident, 
for instance, from the chapter “Die pkysiologische Bedeutung der 
Gerbsauren” in Czapek’s Biochemie der Pflanzen *), where Wigand’s 
view and that of Th Hartig 2 ) concerning “Gerbmehl” as carrier of 
tannin and organized reserve material is reckoned among the “irrigen ; 
Auffassungen tiber die physiologische Rolle der Gerbsauren”. Wigand 
has not published the details of the observations on which his con¬ 
clusions are based and this has probably contributed to the ready 
rejection of his results by other authors 8 ). 
The conception of the role of tannins arrived at by Sachs 4 ) in 
his investigations on the germination of seeds, has received more 
support than that of Wigand. Sachs considered the tannins formed 
in germination, to be merely excretory products, by-products or 
decomposition products. He thought it very improbable that tannins 
could serve in some way or other as material for the building up 
of cell-walls. 
The results of some other observers agree with those of Sachs. 
Thus for instance Kraus*), who was particularly interested in the 
physiological significance of tannins, arrived at the conclusion that 
tannin, once formed, in no case takes any further part in metabolism. 
According to Gerber *) the tannins disappear by oxidation, without^ 
the formation of carbohydrates from them. Af Klercker 7 ) regards 
~ l ) l.c. p. 588. 
2 ) Th. Hartig, Das Gerbmehl, Bot. Zeitung 23. Jahrg. N°. 7,1865, p. 53. Weitere 
Mitteilungen das Gerbmehl betreffend, Bot. Zeitung 23. Jahrg. N®. 30,1865, p. 235. 
3 ) Compare Emil Kbtscher, Ueber die Verwendung der Gerbsaure im Stoff- 
wechsel der Pflanze, Flora, 66. Jahrg. N°. 3, 4 and 5, 1883, p. 37. 
4 ) J. Sachs, Physiologische Untersuch ungen tiber die Keimung der Sehmink- 
bohne t Phased us multiflorus), Sitzungsber. d. kais. Akad. der Wiss. Wien, 37. 
Bd., 1859, No. 17, p. 57. Zur Keimungsgesehichte da- Dattel, Bot. Zeitung, 20. 
Jahrg., 1862, No. 31, p. 241 and 249. Handbuch der Experimental-Physiologic 
der Pflanzen, 1865, p. 360. 
B ) G. Kraus, Grundlinien einer Physiologie des Gerbstoffc, 1889, p. 38 and 44. 
«) G. Gerber, Role des tannins dans les plantes et plus particuherement dans 
les fruits. Compt. rend. 124, p. 1106. 
7 ) J. E. F. Af Klercker, Studien fiber die Gerbstoffvacuolen. Bihang till K. Svenska 
Vit.-Akad. Handlingar, Bd. 13. Aid. Ill, No. 8, 1888. Ref. Bot. Zeitung, 47. Jahrg. 
1889, p. 210. 
