C.— GEOLOGY. 59 
his reason should temper his power, and he should realise the enormous 
responsibility that has fallen into his hands. 
Among the lower races the struggle for existence goes on, and the 
weaker is dispossessed by the stronger; the individual, however, profits 
but little from the activities of his fellows (with exceptions). With man 
the case is entirely different ; the community, the nation, the race, all 
benefit, perforce, through the exertions of a few individuals. In doing 
honour to the great investigators and discoverers, let us not forget that 
they have not only conferred on us great material advantages, but they 
have helped us onward on the great road of increasing complexity. 
Evolution. 
The literature of this subject has so expanded, and nicety of definition 
has received so much attention, that one is almost afraid to use the word 
‘evolution’. Perhaps it would be better to follow Joseph, and say ‘ the 
modification of species through descent’, and leave to biologists and 
psychologists the hair-splitting as to the meaning of evolution, emergence, 
development, &c. To the geologist the fact of organic descent is of prime 
importance, and in the geological evidence lies the chief foundation of 
evolution, define it as you may. 
This doctrine has passed beyond the realm of the scientist and has 
profoundly affected human thought in general ; it may be regarded, there- 
fore, as well within the scope of this address. I have no intention of writing 
an essay on the subject, but I wish to take advantage of the opportunity 
to emphasise certain aspects that have appealed to me as fundamental. 
I would remind you, also, that the geological aspect of evolution is admir- 
ably presented in the Presidential Address of Dr. F. A. Bather, read at the 
Cardiff meeting in 1920. 
Geological investigation has established, beyond all doubt, the basic 
facts that life has changed during the course of the ages, that this change 
has been uniform in direction over the whole globe, and that the general 
tendency has been towards greater complexity both in physical structure 
and in mental equipment. It has been established, further, that in certain 
instances, sequences are found indicating the gradual passage of one 
species into another. This observation is not necessarily a proof of 
descent, but it is a strong argument in its favour. 
Life appeared on the globe in Precambrian time ; of its inception we 
shall probably never be able to obtain direct evidence. In course of time, 
however, recognisable protoplasmic units appeared—unicellular creatures 
neither plant nor animal. The second great event in life history occurred 
somewhat later in the Precambrian—the separation of the parent stem 
into ancestral plants and ancestral animals. Here I would like to 
emphasise the fact that the difference between plants and animals lies, 
not only in the different nature of the metabolism, but in the possession 
_ by the latter of a sensibility or mental equipment so vastly superior, that 
we are accustomed to think of it as absent in the vegetable world. In 
order to simplify our inquiry, let us confine the question to the animal 
‘stem, and let us imagine the primitive creature to be a generalised proto- 
zoan, as sooner or later it was. Within the Precambrian occurred a third 
great organic event of tremendous significance—the Protozoa gave rise 
to the Metazoa. Having accomplished this feat, the ancestral Protozoa 
