Transactions of the Royal Society of Canada 



SECTION V 

 Series III MAY, 1922 Vol. XVI 



I. The Occurrence and Functions of Tannin i7i the Livijig Cell 

 By Francis E. Lloyd, M.A., F.R.S.C. 

 (Presidential address, Section V, May Meeting, 1922) 



In 1913, J. Dekker, of the Koloniaal Museum, Haarlem, Holland, 

 published a Memoir on the Tannins (1913), which is a compilation 

 and critical survey of the whole field, viewed from both botanical 

 and chemical points of view. This work is a monument to the 

 industry of its author, and if omissions are to be found yet it is as 

 nearly complete as may humanly be expected — sufficiently so at any 

 rate to afford a most satisfying and detailed resume of our knowledge 

 as it stood ten years ago. It may, therefore, appear superfluous at 

 so near a date to offer another review of the subject. Nevertheless, 

 I venture to take this occasion to do so — finding for justification that 

 for the botanist an examination of the question from his point of 

 view directs his thought to some fundamental questions of plant 

 physiology. These may presently be briefiy indicated, in order to 

 engage the attention more especially to them rather than to the 

 numerous details available. It must be prefaced, however, that I 

 must be permitted to use the term "tannin" to cover a possibly wide 

 variety of allied substances presenting similar but not identical 

 structure. 



The questions which present themselves for consideration are the 

 following: 



(1) In view of its precipitating action on albuminoids it is 

 inferred to be a protoplasmic poison. How, then, is this protoplasm 

 protected against the action of tannin? (2) Is this substance once 

 formed of further use, and what is its ultimate fate? Although it 

 must be admitted at the outstarl that to answer these questions is 

 not possible at present, nevertheless I may be permitted to ask 

 your attention to some evidence w^hich demands consideration before 

 answers are attempted. 



It is generally believed that when tannin occurs in the living cell 

 it is in the form of a solution in the sap vacuoles. Such vacuoles 

 have sometimes been regarded as specific, but it is probable that 

 tannin vacuoles are nothing more or less than ordinary vacuoles in 



