PRESIDENTIAL ADDRESS. 665 
hope thas I may be dealt with after the manner prayed for by a youthful 
examinee whose paper, which I read, contained the appeal: ‘Mr. Examiner, 
please temper justice with mercy, for I am so young in mind.’ This hope I 
base upon the facts that modern science has at least taught tolerance, and that 
I have ever found my botanist colleagues conspicuous for this virtue. They 
understand that even the most minor among prophets prefers the stake to 
silence, and their good humour acquiesces in the interchange of ré/es whereby 
the martyrdom which shou!d be his is borne by them in listening to his wrathful 
words. 
Anticipation of toleration so undeserved leads me to regret almost that I ever 
introduced that ghost at all. For now that it has served my purpose I am free 
to admit that I might have laid it long ago by other and tu-quoque arts. 
I, too, might have pointed to those shelves, and at the sight of Mendel’s work 
it would have vanished with a blush. Fer with all their gracious gifts the 
Victorians whose just praises I have sung failed to discover that Mendel was alive 
among them, and showing a way to solve the problems over which they themselves 
were puzzling. 
The merit of the discovery of the greatness of Mendel’s work belongs to our 
generation, and those of us who had no share in it have at least the right to 
applaud the discoverers and to score the discovery to our side. 
So I may conclude the contrast of Victorian with modern naturalists with the 
reflection: theirs, the higher meed of culture; ours, perhaps, the greater 
perspicacity. 
If, as I am prepared to maintain, the greatest gift which an experimental 
science may receive is that of a new, serviceable, general method. then to no 
man are biologists more indebted than to Mendel, for such a method he gave 
to our science. If, further, this claim can be established, I am absolved from 
the task of answering the critics of Mendelian doctrine. 
Who does not recollect the answer which John Hunter gave to someone— 
Jenner, perhaps—who wrote to that creat experimenter expressing doubt of the 
validity of an hypothesis? ‘ Don’t think—try,’ was Hunter’s fine response. 
If it were my purpose to discourse on Mendelian doctrine it would be my duty 
to carry on that work-—like the early builders of that doctrine—with sword in 
one hand and trowel in the other, and to try in emulation of the pioneers to take 
an equal joy in using either implement. But my work concerns the method and 
facts accomplished by its use, and, as I understand philosophy, the writ of 
criticism does not run in the domain of accomplished fact. A homely illustra- 
tion will serve to define my attitude. Here is a new knife, and there an old loaf, 
the crust of which has turned the edge of other implements. If with this knife 
I cut that loaf, it is idle to tell me that my knife is blunt. One form of 
criticism, and one only, is valid in such circumstances, and that is the constructive 
criticism of offering a better instrument. If I want bread, and Mendel’s knife 
can give it. to me, I shall go on cutting, indifferent to the stones of destructive 
criticism. 
My business, therefore, is to meet criticism not by dialectics, but by confront- 
ing it with the facts accomplished by this method and by showing that its use 
opens new pathways on the borders of the unknown. 
Now, if we scrutinise the method of Mendelian research, we may see that there 
can be no criticism of it. 
Give a chemist a complex mixture of many compounds to describe : how does 
he proceed? The chemist sorts out the ingredients. and submits them severally 
to analysis. Such, also, is the method of the Mendelian analyst. Give him that 
complex mixture which is called an individual, and he sorts out the ingredients 
and submits them to analysis. Ask him how two complex mixtures behave when 
they are bred together, and he re-defines the question in such terms that it ceases 
to be enigmatical, and becomes susceptible of solution by experiment. 
I am not concerned to claim for the Mendelian method the exclusive possession 
of these virtues. . All I claim is that for the work of making a physiological 
analysis of individuals, and of thereby establishing a physiological classification 
of plants and animals, the Mendelian method has proved its value. It effects the 
service by a simultaneous analysis of germ and soma. 
Let it be conceded at the outset that this analysis is made not by direct 
