PRESIDENT S ADDRESS. 
297 
ever, does not contain glucoside, just as the seed of the bitter 
almond, which there is reason to believe is produced by the 
cultivation of Prunus amygdalus, contains no glucoside. It 
is impossible, without further knowledge of the causes which 
influence plants in the selection of reserve materials, to offer 
any explanation of the fact that these glucosides appear as 
reserve materials in the seeds of Phaseohis lunatics and in 
those of the bitter almond, but not in those of Lotus arabicus 
and Sorghum vulgare. 
“ The reason for the disappearance of cyanogenetic 
glucosides from the seeds of Phaseolus lunatics and the bitter 
almond when cultivated, is probably to be found in the 
stimulus to metabolism resulting from improved nutrition 
and environment. These, as is well known, lead to the more 
rapid utilisation of plastic substances, with the result that 
there is very little, or possibly none, of the cyanogenetic 
glucoside available for storage as reserve material in the 
seeds of the cultivated plant. The enzymes, on the other 
hand, are aplastic or stable substances, performing definite 
synthetical and analytical functions without themselves 
undergoing change, and consequently it is to be expected 
that they would be found alike in the seeds of the wild and 
of the cultivated plants. The enzyme emulsin occurs in the 
seeds of the cultivated Phaseolus lunatics as well as in those 
of the sweet almond, although the cyanogenetic glucoside 
has disappeared under the influence of cultivation.” 
As regards the localization of the vegetable enzymes, in 
the simplest cases of secretion, eg ., the yeast-cell, the enzyme 
is probably co-terminous with the cell protoplasm. In higher 
plants, however, more approach to specialization is seen, 
though even among these there are conspicuous cases of a 
very wide distribution amongst the tissues, as in the case of 
diastase. The enzyme and the glucoside on which it works 
are always enclosed in different cells. In roots they are 
distributed chiefly in the cortex, but sparsely in the wood. 
