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580 REPORT—1904. 
In saying this I mean no disrespect to that study of the physiology of repro- 
duction by histological means, which, largely through the stimulus of Weismann’s 
speculations, has of late made such extraordinary advances. It needs no pene- 
tration to see that, by an exact knowledge of the processes of maturation and 
fertilisation, a vigorous stock is being reared, upon which some day the experience 
of the breeder will be firmly grafted, to our mutual profit. We, who are engaged 
in experimental breeding, are watching with keenest interest the researches of 
Strasburger, Boveri, Wilson, Farmer, and their many fellow-workers and asso- 
ciates in this difficult field, sure that in the near future we shall be operating in 
common. We know already that the experience of the breeder is in no way 
opposed. to the facts of the histologist ; but the point at which we shall unite will 
be found when it is possible to trace in the maturing germ an indication of some 
character afterwards recognisable in the resulting organism. Till then, in order 
to pursue directly the course of heredity and variation, it is evident that we must 
fall back on those tangible manifestations which are to be studied only by field 
observation and experimental breeding. 
The breeding-pen is to us what the test-tube is to the chemist—an instrument 
whereby we examine the nature of our organisms and determine empirically what 
for brevity I may call their genetic properties. As unorganised substances have 
their definite properties, so have the several species and varieties which form the 
materials of ourexperiments. Livery attempt to determine these definite properties 
contributes immediately to the solution of that problem of problems, the physical 
constitution of a living organism. In those morphological studies which I suppose 
most of us have in our time pursued, we sought inspiration from the belief that in 
the examination of present normalities we were tracing the past, the phylogenetic 
order of our types, the history—as we conceived—of Evolution. In the work 
which I am now pressing upon your notice we may claim to be dealing not only 
with the present and the past, but with the future also. 
On such an occasion as this it is impossible to present to you in detail the 
experiments—some exceedingly complex—already made in response to this newer 
inspiration, I must speak of results, not of methods. At a later meeting, more- 
over, there will be opportunities of exhibiting practically to those interested some 
of the more palpable illustrations. It is also impossible to-day to make use of the 
symbolic demonstrations by which the lines of analysis must be represented. The 
time cannot be far distant when ordinary Mendelian formule will be mere as in 
praesenti to a biological audience. Nearly five years have passed since this extra- 
ordinary re-discovery was made known to the scientific world by the practically 
simultaneous papers of De Vries, Correns, and Tschermak, not to speak of thirty- 
five years of neglect endured before. Yet a phenomenon comparable in signifi- 
cance with any that biological science has revealed remains the intellectual posses- 
sion of specialists. We still speak sometimes of Mendel’s hypothesis or theory, 
but in truth the terms have no strict application. It is no theory that water is 
made up of hydrogen and oxygen, though we cannot watch the atoms unite, and 
it is no theory that the blue Andalusian fowl] I produce was made by the meeting 
of germ-cells bearing respectively black and a peculiar white. Both are incontro- 
vertible facts deduced from observation. The two facts have this in common also, 
that their perception gives us a glimpse into that hidden order out of which the 
seeming disorder of our world is built. If I refer to Mendelian ‘ theory ’ therefore, 
in the words with which Bacon introduced his Great Instauration, ‘I entreat 
men to believe that it is not an opinion to be held, but a work to be done; and to 
be well assured that I am labouring to lay the foundation, not of any sect or 
doctrine, but of human utility and power,’ 
Tn the Mendelian method of experiment the one essential is that the posterity 
of each individual should be traced separately. If individuals from necessity are 
treated collectively, it must be proved that their composition is identical. In 
direct contradiction to the methods of current statistics, Mendel saw by sure 
penetration that masses must be avoided. Obvious as this necessity seems when 
one is told, no previous observer had thought of it, whereby the discovery was 
