( 685 ) 
the atrium show themselves, as they have been described above. 
These alterations in the form of the electrogram, apart from tonic 
changes, are not accompanied bv changes in the motoric utterances. 
Fig. 4. 
The tonic alteration cannot be considered as the cause of the 
changes in form of the electrogram, because, in using still weaker 
currents as stimuli for the n. vagus, the same tonic change may 
appear, without having any effect on the electric utterances of the 
atrium. 
Botany. — 11 On the tests for tannin in the living plant and on the 
physiological significance of tannin” By Mr. C. van Wisselingh. 
(Communicated by Prof. J. W. Moll.) 
(Communicated in the meeting of February 26, 1910). 
In this paper a method will be described for demonstrating the 
presence of tannin in the living plant, a method which enables us 
moreover to obtain an idea of the amount of this substance in the 
living cells, and to ascertain whether after a given period of time 
the amount has increased or diminished ; tho method does not 
noticeably affect the living funtions of the plant or damage the 
latter to an appreciable extent. 
In addition a few results of experiments on the physiological sig¬ 
nificance of tannin will be communicated; these results are in my 
opinion a real contribution to our knowledge of this subject. 
Before proceeding to a discussion of the method which I have 
worked out, I think it desirable to make some observations on the 
meaning of the word “tannin’' and to give an account of the present 
state of the physiological tannin-problem. 
As regards the meaning attached to the word tannin there is no 
uniformity. Botanists formerly meant by tannin every thing in tho 
celt which was coloured blue or green by ferric salts 1 * * * ). This has 
led to confusion with other substances and to the view that tannin 
is a generally occurring constituent of .plants. Reinitzkr 5 ) especially 
has drawn attention to this. As a result of his investigations he came 
to the conclusion that the word tannin is a misnomer, introduced 
into science from the leather industry. According to him it should 
i) j. Dekker, De looistoffen, Bot.-chem. monographic der tanniden, 1908, V. I, 
p. 197 and 210. 
F. Czafek, Biochemie der Pflanzen, II. Bd. p. 576. 
s ) F. Reixitzer, Bemerkungcn zur Physiologic des Gerbstoffs, Ber. d. d. bot. 
Gesellsch. Bd. VII, 1889, p. 187. 
