502 
NATURE 
[SEPTEMBER 21, 1899 
‘or was raised at wide intervals by successive uplifts, or was 
slowly elevated by one prolonged and continuous movement. 
But they might furnish us with suggestive information as to the 
vate at which upheaval or depression of the terrestrial crust is 
now going on. 
The vexed questions of the origin of raised beaches and sunk 
Forests might in like manner be elucidated by well-devised 
measurements. It is astonishing upon what loose and untrust- 
worthy evidence the elevation or depression of coast-lines has often 
been asserted. On shores where proofs of a recent change of 
level are observable it would not be difficult to establish by accurate 
observation whether any such movements are taking place now, 
and, if they are, to determine their rate. The old attempts of 
this kind along the coasts of Scandinavia might be resumed with 
far more precision and on a much more extended scale. Methods 
of instrumental research have been vastly improved since the 
days of Celsius and Linnzus. Mere eye-observations would not 
supply sufficiently accurate results. When the datum-line has 
been determined with rigorous accuracy, the minutest changes 
of level, such as would be wholly inappreciable to the senses, 
might be detected and recorded. If such a system of watch 
were maintained along coasts where there is reason to believe 
that some rise or fall of land is taking place, it would be possible 
to follow the progress of the movement and to determine its 
xate. 
But I must not dwell longer on examples of the advantages 
which geology would gain from a far more general and sys- 
tematic adoption of methods of experiment and measurement in 
elucidation of the problems of the science. I have referred toa 
few of those which have a more special bearing on the question 
of geological time, but it is obvious that the same methods might 
be extended into almost every branch of geological dynamics. 
While we gladly and gratefully recognise the large amount of 
admirable work that has already been done by the adoption of 
these practical methods, from the time of Hall, the founder of 
experimental geology, down to our own day, we cannot but feel 
that cur very appreciation of the gain which the science has thus 
derived increases the desire to see the practice still further 
multiplied and extended. I am confident that it is in this 
direction more than in any other that the next great advances 
of geology are to be anticipated. 
While much may be done by individual students, it is less 
to their single efforts than to the combined investigations of 
many fellow-workers that I look most hopefully for the ac- 
cumulation of data towards the determination of the present 
rate of geological changes. I would therefore commend this 
subject to the geologists of this and other countries as one in 
which individual, national and international co-operation might 
well be enlisted. We already possess an institution which 
seems well adapted to undertake and control an enterprise of 
the kind suggested. The International Geological Congress, 
which brings together our associates from all parts of the globe, 
would confer a lasting benefit on the science if it could 
organise a system of combined observation in any single one of 
the departments of inquiry which I have indicated or in any 
other which might be selected. We need not at first be too 
ambitious. The simplest, easiest and least costly series of ob- 
servations might be chosen for a beginning. The work might 
be distributed among the different countries represented in the 
Congress. Each nation would be entirely free in its selection 
of subjects for investigation, and would have the stimulus of 
co-operation with other nations in its work. The Congress 
will hold its triennial gathering next year in Paris, and if such 
an organisation of research as I have suggested could then be 
inaugurated a great. impetus would thereby be given to geo- 
logical research, and France, again become the birthplace of 
another scientific movement, would acquire a fresh claim to 
the admiration and gratitude of geologists in every part of the 
globe. ; 
SECTION D. 
ZOOLOGY. 
OPENING ADDRESS BY ADAM SEDGWICK, 
PRESIDENT OF THE SECTION. 
M.A., F.R-S., 
Variation and some Phenomena connected with Reproduction 
and Sex. 
IN the following Address an attempt is made to treat the facts 
of variation and heredity without any theoretical preconceptions. 
The ground covered has already been made familiar to us by 
NO. 1560, VOL. 60| 
the writings of Darwin, Spencer, Galton, Weismann, Romanes 
and others. I have not thought it advisable to discuss the 
theories of my predecessors, not from a want of appreciation of 
their value, but because I was anxious to look at the facts them- 
selves and to submit them to an examination which should be 
as free as possible from all theoretical bias. 
Zoology is the science which deals with animals. Knowledge 
regarding animals is, for convenience of study, classified into 
several main branches, amongst the most important of which 
may be mentioned : (1) the study of structure ; (2) the study of 
the functions of the parts or organs; (3) the arrangement of 
animals in a system of classification; (4) the past history of 
animals; (5) the relations of animals to their environment ; 
(6) the distribution of animals on the earth’s surface. That 
part of the science of zoology which deals with the functions of 
organs, particularly of the organs of the higher animals, is fre- 
quently spoken of as physiology, and separated more or less 
sharply from the rest of zoology under that heading. So strong 
is the line of cleavage between the work of the physiologist and 
that of other zoologists, that this Association has thought it ad- 
visable to establish a special Section for the discussion of 
physiological subjects, leaving the rest of zoology to the con- 
sideration of the old established Section, D. In calling attention 
to this fact, I do not for one moment wish to question the 
advisability of the course of action which the As-ociation has 
taken. The science of physiology in its modern aspects includes 
a vast body of facts of great importance and great interest which 
no doubt require separate treatment. But what I do wish to 
point out is that it is quite impossible for us here to abrogate 
all our functions as physiologists | Some of the most important 
problems of the physiological side of zoology still remain within 
the purview of this Section. 
For instance, the important and far-reaching problems con- 
nected with reproduction and variation are very largely left to 
this Section, and that large group of intricate and almost en- 
tirely physiological phenomena connected with the’ adaptations 
of organisms to their environment are dealt with almost ex- 
clusively here. Indeed, we may go further, and say that apart 
altogether from practical questions of convenience, which make 
it desirable to separate a part of physiological work from the 
Zoological Section, it is, as a matter of fact, impossible to 
divorce the intelligent study of structure from that of function. 
The two are indissolubly connected together. The differ- 
entiation of structure involves the differentiation of function, 
and the differentiation of function that of structure. The con- 
ceptions of structure and function are as closely associated as 
those of matter and force. A zoologist who confined: himself 
to the study of the structure of organisms, and paid no atten- 
tion to the functions of the parts, would be as absurd a person 
as a philologist who studied the structure of words and took no 
account of their meaning. In the early part of this century, 
when the subject-matter of zoology was not so vast as it is at 
present, this aspect of the case was fully recognised, and one of 
the greatest zoologists of the century, whether considered from 
the point of view of modern anatomy, or of modern physiology, 
was Professor of Anatomy and Physiology at the University of 
Berlin. 
Having said that much as to the various aspects of living 
nature, of natural history, if you like, which it falls within 
the province of this Section to deal with, I may now proceed 
to the subject of my address. And when I mention to you 
what that subject is, you will be able to make some allowance 
for the somewhat commonplace remarks with which I have 
treated you. For that subject, though it has its important 
morphological aspects, is in the main a physiological one; at 
any rate, no study which does not take account of the ‘physio- 
logical aspect of it can ever hope to satisfy the intellect of man. 
The subject, then, to which I wish to draw your attention at 
the outset of our proceedings, is the great subject of Variation 
of Organisms. : : 
As every one knows, there is a vast number of different kinds 
of organisms. Each kind constitutes a species, and consists of 
an assemblage of individuals which resemble one another more 
closely than they do other animals, which transmit their 
characteristics in reproduction and which habitually live and 
breed together. But the members of a species, though re- 
sembling one another more closely’ than they resemble the 
members of other species, are not -absolutely alike. They pre- 
sent differences, differences which make themselves apparent 
