106 SECTIONAL ADDRESSES. 
competition, they have no chance in the struggle for existence unless they 
show rapid improvement and development of the favourable variations 
within a few generations. Hence the numbers exhibiting each of the early 
stages of change will always be few and the chances of their preservation ~ 
slight. Those who have tried to work out the stages in the history of an 
invention, for instance, will appreciate the rarity of ‘ missing links’ and 
the difficulty of fillg in every step towards the later perfection. These 
are looked upon as ‘freaks’ and, unless they present real and marked 
improvement, are never manufactured on a large scale. Their numbers 
consequently are few, and many of them are the victims of experiment 
and often do not survive the experience. 
5. Perhaps the most wonderful result disclosed by a study of the later 
part of the geological record is the steady and unbroken evolution of brain 
from the earliest vertebrate animals to the present. The exceeding 
slowness of the process in its early stages is not less wonderful than its 
acceleration during the latest stages of geological history. The disappear- 
ance of so many orders of reptiles at the end of the Mesozoic Period, at the 
close of a long and most promising chain of evolution, indicates that there 
was some inherent weakness underlying the line of evolution entered upon 
by them, which proceeded so far and favourably that it was impossible to 
retrace the path. This may well have been connected with the substance 
or construction of brain and nerve. If so, this side of evolution has to be 
seriously reckoned with, and it may be that the fundamental weakness of 
physical as opposed to intellectual evolution brought this flourishing and 
well-developed group to its end. 
It has, of course, been suggested by Searles V. Wood, jun. (Phil. Mag. 
xxiii, 1862), and others, that the destruction of Mesozoic life types was 
brought about by physical changes; but, apart from the fact that the 
particular changes supposed by the former did not as a matter of fact 
occur, the entire explanation provides a cause utterly insufficient in com- 
parison with the potency of organic struggle against creatures better 
endowed with warm blood, adequate brain substance, and the activity 
and enterprise springing therefrom. 
In spite of the evidence of acceleration as the higher ranks of animals 
are reached, and in spite of the extraordinary efficiency of the human 
brain and all the benefits to the organism it brings about, we may well 
be appalled by the zons which have been used up and the millions of varie- 
ties which have passed away in the production of this, the most efficient 
scientific apparatus yet invented or evolved. 
6. But if it has taken long ages to evolve an animal capable of a 
broader geographical distribution than any other, with aconstitution capable 
of withstanding the widest ranges of heat and cold and of peopling the 
world from its tropical deserts to its polar wastes ; and to endow him with 
a brain by virtue of which he has made himself master of the earth and all 
its living inhabitants; it has taken no less time for the evolution of the 
many factors without which his present success would have been impossible. 
To pick out a single instance, probably few things in the whole story of 
life have been more fruitful in effect than the appearance of the grasses 
in Late Hocene times, followed by their rapid evolution and spread in the 
Oligocene and under the direction of the critical events of the Miocene 
Period. Starkie Gardner in an admirable paper first drew attention to 
