274 
THE FUNCTION OF TANNIN. 
Sachs,* * * § in liis researches into the germination of 
Phaseolus multiflonis (the scarlet-runner kidney bean) says, 
“ Den 1 eicht bewegliclien Kohlenhydraten und Eiweissstoffen 
gegeniiber bilden der Gerbstoff und die Farbstoffe eine Gruppe 
trager Elemente, da sie, wo sie einmal entstanden sind, liegen 
bleiben. Diese beiden Gruppen sind in der That pliysiolo- 
giscli in jeder Hinsicht verschieden ; Kohlenhydrate und 
Eiweissstoffe sind in ruhenden Keim vorhanden, sie sind 
niclit das erste, sondern das letzte Assimilationsprodukt 
der Mutterpflanze, ein fur Naclikommen aufgespartes Capital; 
Gerbstoffe und Farbstoffe dagegen treten auf an den Stellen 
wo die Vegetation beginnt, wo jene Assimilationsprodukte der 
Mutterpflanze nur in neue Form ubergehen. Der Gerbstoff, 
und der mit ilim in denselben Zellen enthaltene Farbstoff 
scheinen Nebenprodukte des Cliemismus in producirenden 
Gewebe.’G This sentence is the foundation of the views of 
one body of vegetable physiologists, that tannin is a bye- 
product of assimilation. In this connection it ought, how¬ 
ever, to be pointed out that the tannin of Phaseolus is, in 
many respects, quite unlike the tannins so commonly met 
with in the cortex, &c. of woody plants. 
WigandJ believed that tannin forms an essential factor 
in the chemical processes of plant life, and always physiolo¬ 
gically as a member of the series of carbohydrates. Always 
appearing in opposition to starch, it in general seems to play 
a part in the series of materials possessing formative energy, 
though in some cases it also acts as a reserve material. 
Nothing could be more diametrically opposed to the view of 
Sachs than this. 
Wagner § endeavoured to distinguish a pathological from 
a physiological tannin, based on their varying relations to 
ferments and dilute acids ; but it is not apparent that he 
intended by his choice of classificatory terms to convey any 
idea of the physiological significance of tannin to the plant. 
* Sachs , “Ueber die Keimung von Phaseolus multiflorus; ” Sitz. 
der Wien. Akad., 1859, pp. 57, et seq. 
f The gist of this sentence is that the carbohydrates and albumins 
on the one hand, and the tannins and colour bodies on the other, 
are physiologically opposites. The former are products of the mother 
plant stored within the seed ; the latter appear with renewed growth, 
simultaneously with the chemical changes in the stored food materials, 
and are probably, therefore, bye-products of these changes. 
$ Wigand , “ Einige Siitze ii. d. physiologisclie Bedeutung des 
Gerbstoffes und der Pflauzenfarben ” ; But. Zeit., 1862, pp. 121-5. 
§ Wagner , “ Beitriige zur Kenntniss u. s. w. der Gerbsauren,” 
Journ. f. Prakt. Cliemie., Bd. 99, 1866, pp. 294-305. 
