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PRESIDENT S ADDRESS. 
The pericycle and the tissue derived from it form their chief 
seat. In leaves the secreting cells occur throughout the 
mesophyll. In flowers secreting cells are contained in large 
numbers in both sepals and petals, but they are most 
numerous in the pulp of the fruit, whilst in seeds they may 
occur in the embryo and integument, in the parenchyma 
of the cotyledons, and in the lower epidermis when the 
cotyledons become green. 
We have seen that enzyme and glucoside must, in the 
words of Emil Fischer, “ fit each other like lock and key,” if 
the one is to have chemical action on the other. 
To study other chemical and physical properties of 
enzymes not touched in our consideration of the particular 
case of cyanogenesis we must pass on to other fields of vital 
activity. For instance, the phenomena of the fermentation 
of sugar to alcohol and carbonic acid, and the conversion of 
starch to sugar, eg ., in the germination of the barley-grain, 
afford admirable fields for their study. So does recent work 
such as that of Usher and Priestley, on the fascinating but 
elusive chemistry of the leaf cell. It is to the action of 
enzymes present in the living protoplasm that we must look 
for the selective analytic and synthetic power of the plant cell. 
This I may say in conclusion : the more we probe into 
these phenomena the more convinced we shall be that the 
living organism as a chemical agency has as yet been made 
to reveal but a small portion of its mysteries, and that the 
facts which have been hitherto wrested from Nature in the 
region of biochemistry are but fragments of the whole truth. 
But so much light is dawning that we may regard the future 
cheerfully and confidently, rejecting the definition of the 
modern man of science as “a blind man in a churchyard at 
midnight, trying to read epitaphs in a forgotten tongue,” and 
believing that the chemist and physiologist may yet “ track 
suggestion to her inmost cell.” 
In answer to questions as to the practical bearings of the 
