Nov. 1906. | THE PRESIDENTIAL ADDRESS. 227 
ferment which, when in water if comes in contact with the 
glucoside xanthorhamnin located in the pericarp, breaks it up 
into glucose and the crystalline yellow rhamnin which is the 
matter of the yellow dye of the Persian berries, as the fruits 
of Rhamnus are called. By this discovery he gave the 
scientific explanation of empirical points that troubled 
dyers. Why, for instance, the crushed fruits yield a satis- 
factory colouring matter, whilst the pericarps alone do 
not. Further, he advanced reasons for thinking that the 
vlucoside is a storage material for the young plant, quoting 
as analogous cases the well-known ones of the amygdalin 
glucoside and emulsin present in separate cells of the seed 
of bitter almond, and the myrosin ferment and myronate of 
potassium in mustard. 
[I mention these researches first because they are the 
only cases of elaborate investigation published by Marshall 
Ward outside the group of the Fungi, Mycetozoa, and Bacteria. 
They show, however, that in any field he entered upon he 
would have obtained brilliant results. 
The critical moment that determined the chief field of 
Marshall Ward’s research was that when in 1879 he was 
appointed to investigate in Ceylon the coffee-leat disease. 
From that moment Fungi in the widest sense and their 
work were the subject of his assiduous research. On him in 
fact descended the mantle of Berkeley, our great Cryptogamic 
botanist of the nineteenth century. During the past couple 
of decades Marshall Ward has been our recognised authority 
upon the group and its activities, and he has given us story 
after story of the life and inter-relations of different forms, 
sketched with the accuracy of observation and judgment of 
circumstance that beeame one who had been in touch with 
De Bary and through him had aequired the tradition of the 
school of the Tulasnes. Dominating all his brilliant inquiries 
is the endeavour to solve the questions involved in parasitism 
—the influence exercised by the host on the parasite, and 
conversely of the parasite on the host and the mechanism 
of the attack—in fact, the fundamental problem of the 
interaction of living organisms. 
His first study in this group was that of Hemleia 
vastatriz, the fungus of the coffee-leaf disease. It will be 
within knowledge of many of you that in the seventies the 
