Ie 
NALRORLE. 
| DECEMBER 6, 1906 
interest in it.’’ A little more discretion on the part of 
readers of papers in having regard to the composition of 
their actual audience would be helpful here. In some cases 
experimental illustration would bring home to a larger 
number what is followed with difficulty from a merely 
verbal statement. But I am afraid that no complete 
remedy is within reach. 
Increase of specialisation, however inconvenient in some 
of its aspects, is, I suppose, a necessary condition of pro- 
gress. Sometimes a big discovery, or the opening up of 
a new point of view, may supersede detail and bring unity 
where before there was diversity, but this does not suffice 
to compensate the general tendency. Even in mathematics, 
where an outsider would probably expect a considerable 
degree of homogeneity, the movement towards diversity is 
very manifest. Those who, like myself, are interested 
principally in certain departments, and can look back over 
some forty years, view the present situation with feelings 
not unmixed. It is disagreeable to be left too far behind. 
Much of the activity now displayed has, indeed, taken a 
channel somewhat remote from the special interests of a 
physicist, being rather philosophical in its character than 
scientific in the ordinary sense. Much effort is directed 
towards strengthening the foundations upon which mathe- 
matical reasoning rests. No one can deny that this is a 
laudable endeavour, but it tends to lead us into fields 
which have little more relation to natural science than has 
general metaphysics. One may suspect that when all is 
done fundamental difficulties will still remain to trouble 
the souls of our successors. Closely connected is the de- 
mand for greater rigour of demonstration. Here I touch 
upon a rather delicate question, as to which pure mathe- 
maticians and physicists are likely to differ. However 
desirable it may be in itself, the pursuit of rigour appears 
sometimes to the physicist to lead us away from the high 
road of progress. He is apt to be impatient of criticism 
whose object seems to be rather to pick holes than to 
illuminate. Is there really any standard of rigour inde- 
pendent of the innate faculties and habitudes of the par- 
ticular mind? May not an argument be rigorous enough 
to convince legitimately one thoroughly imbued with certain 
images clearly formed, and yet appear hazardous or even 
irrelevant to another exercised in a different order of ideas? 
Merely as an example, there are theorems known as 
“existence-theorems ”? having physical interpretations, the 
object of which is to prove formally what to many minds 
can be no clearer afterwards than it was before. The pure 
mathematician will reply that, even if this be so, the intro- 
duction of electrical or thermal ideas into an analytical 
question is illogical, and from his own point of view he 
is, of course, quite right. What is rather surprising is 
that the analytical argument should so often take forms 
which seem to have little relation to the intuition of the 
physicist. Possibly a better approach to a reconciliation 
May come in the future. In the meantime we must be 
content to allow the two methods to stand side by side, 
and it will be well if each party can admit that there is 
something of value to be learned from the point of view 
of the other. 
In other branches, at any rate, the physicist has drawn 
immense advantage from the labours of the pure analyst. 
I may refer especially to the general theory of the complex 
variable and to the special methods which have been 
invented for applying it to particular problems. The 
rigorous solution by Sommerfeld of a famous problem in 
diffraction, approximately treated by Fresnel, is a case in 
point. We have moved a long way from the time when 
it was possible for the highest authority in theoretical 
optics to protest that he saw no validity in Fresnel’s inter- 
pretation of the imaginary which presents itself in the 
expression for the amplitude of reflected light when the 
angle of incidence exceeds the critical value. In this con- 
nection it is interesting to remember that, in his corre- 
spondence with Young, Laplace expressed the opinion that 
the theoretical treatment of reflection was beyond the 
powers of analysis. The obvious moral is that we are not 
to despair of the eventual solution of difficulties that may 
be too much for ourselves. 
As more impartially situated than some, I may, perhaps, 
venture to say that in my opinion many who work entirely 
upon the experimental side of science underrate their obli- 
NO. 1936, VOL. 75 
gations to the theorist and the mathematician. Without 
the critical and coordinating labours of the latter, we 
should probably be floundering in a bog of imperfectly 
formulated and often contradictory opinions. Even as it 
is, some branches can hardly escape reproaches of the kind 
suggested. I shall not be supposed, I hope, to under- 
value the labours of the experimenter. The courage and 
perseverance demanded by much work of this nature is 
beyond all praise; and success often depends upon what 
seems like a natural instinct for the truth—one of the 
rarest of gifts. 
Copley Medal. 
The Copley medal is awarded to Prof. Elias Metchnikoff, 
For.Mem.R.S., on the ground of his distinguished services 
to zoology and to pathology, particularly for his observ- 
ations on the development of invertebrates and an phago- 
cytosis and immunity. From 1866 to_1882 Prof. Metch- 
nikoff’s work was exclusively zoological, and mainly 
during that period he produced a series of brilliant 
memoirs dealing with the early development and meta- 
morphoses of invertebrates. 
Although his name stands in the first rank of investi- 
gators of these subjects, the most celebrated of his dis- 
coveries are those relating to the important part played by 
wandering mesoderm cells and white blood-corpuscles in 
the atrophy of larval organs, and in the defence of the 
organism against infection by bacteria and protozoa. It 
was on these researches that he based his well-known 
“phagocyte theory.’ Metchnikoff’s fundamental observ- 
ations were made in Messina in 1882, and were published 
in the following year. In these he showed that the absorp- 
tion and disappearance of the embryonic organs of echino- 
derms were effected by wandering mesoderm cells, which 
devoured and digested the structures which had served their 
purpose and become effete. The observation that white 
blood-cells accumulate in an inflamed area after infection 
by bacteria suggested that these cells might also devour 
and thus destroy the invading microbes, and that the 
process of inflammation was really a physiological and 
protective reaction of the organism against infection. The 
study of the infection of Daphnia by Monospora bicuspidata 
entirely justified this prediction. The account of the 
phenomena of infection as seen in this transparent 
crustacean was published in Virchow’s Archiv (vol. 
xcvi.) in 1884, while, later in the same year, Metchnikoff 
published another paper extending these observations to 
vertebrates, and showing the universal applicability of his 
generalisation as to the essential character of the in- 
flammatory process. 
During the twenty years which have elapsed since the 
publication of the ‘‘ phagocyte theory,’? Metchnikoff, with 
the assistance of a host of pupils and disciples from all 
parts of the world, has been continuously engaged in the 
study of the reaction of the organism against infection, 
and in investigating the essential features of immunity in 
the light of the illuminating generalisation laid down in 
1884. 
Though of limited range, and therefore inferior in scien- 
tific importance to the more fundamental researches carried 
out by him previously, Metchnikoff’s recent work on in- 
fection by the microorganism of syphilis and the attain- 
ment of protection and immunity against this disease may 
be mentioned on account of its important practical 
applications. 
It is not too much to say that the work of Metchnikoff 
has furnished the most fertile conception in modern path- 
ology, and has determined the whole direction of this 
science during the last two decades. 
Rumford Medal. 
The Rumford medal is awarded to Prof. Hugh Long- 
bourne Callendar, F.R.S., for his experimental worl on 
heat. 
Prof. Callendar has devoted his attention chiefly to the 
improvement of accurate measurement in the science of 
heat by the application of electrical methods. His first 
paper, ‘‘ On the Practical Measurement of Temperature,”’ 
Phil. Trans., 1887, paved the way for the application of 
the electrical resistance thermometer to scientific investi- - 
gation. In a later paper, written in conjunction with 
