808 REPORT—1896. 
Section D.—ZOOLOGY. 
PRESIDENT OF THE SEecTION—E. B. Pourton, M.A., F.R.S., F.L.S., Professor of 
Zoology in the University of Oxford. 
THURSDAY,.SEPTEMBER 17. 
The President delivered the following Address :— 
A Naruratist’s ConTRIBUTION TO THE DISCUSSION UPON THE AGE OF 
THE EARTH. 
A very brief study of the proceedings of this Section in bygone years will show 
that Presidents have exercised a very wide choice in the selection of subjects. At 
the last Meeting of the Association in this city in 1870 the Biological Section had as 
its President the late Professor Rolleston, a man whose remarkable personality 
made a deep impression upon all who came under his influence, as I have the 
strongest reason for remembering, inasmuch as he was my first teacher in zoology, 
and I attended his lectures when but little over seventeen. His address was most 
characteristic, glancing over a great variety of subjects, literary as well as scientific, 
and abounding in quotations from several languages, living and dead. A very 
different style of address was that delivered by the distinguished zoologist who 
presided over the Meeting. Professor Huxley took as his subject ‘The History of 
the Rise and Progress of a Single Biological Doctrine.’ 
O ithese two types I selected the latter as my example, and especially desired 
to attempt the discussion, however inadequate, of some difficulty which confronts 
the zoologist at the very outset when he begins to reason from the facts around 
him—a difficulty which is equally obvious and of equal moment to the highly 
trained investigator and the man who is keenly interested in the results obtained 
by others, but cannot himself lay claim to the position and authority of a skilled 
observer—to the naturalist and to one who follows some other branch of know- 
ledge, but is interested in the progress of a sister science. 
Two such difficulties were alluded to by Lord Salisbury, in his interesting presi- 
dential address to the British Association at Oxford in 1894, when he spoke of 
‘two of the strongest objections to the Darwinian explanation’ of evolution—viz., 
the theory of natural selection—as appearing ‘ still’to retain all their force.’ The 
first of these objections was the insufficiency of the time during which the earth 
has been in a habitable state, as calculated by Lord Kelvin and Professor Tait, 
100 million years being conceded by the former, but only ten million by the latter. 
Lord Salisbury quite rightly stated that for the evolution of the organic world as 
we know it by the slow process of natural selection at least many hundred 
million years are required; whereas, ‘if the mathematicians are right, the biologists 
cannot have what they demand. . . . The jelly-fish would have been dissipated in 
steam long before he had had a chance of displaying the advantageous variation 
which was to make him the ancestor of the human race.’ 
The second objection was that ‘we cannot demonstrate the process of natural 
selection in detail; we cannot even, with more or less ease, imagine it.’ ‘In 
natural selection who is to supply the breeder’s place ?’ ‘There would be nothing 
