104 SECTIONAL ADDRESSES. 
be mere scraps of paper, but from the intensive application to them of 
the very science which has evolved them. 
Although the geological record is and possibly will always remain 
incomplete, it has yet proved remarkably representative, and certain out- 
standing facts have been made out which are sufficient to show that the 
lines of organic evolution as recorded in geology are in accordance with 
what is theoretically probable, and with those taken by the evolution of 
domesticated organisms and by human arts and inventions. 
1. There can be no doubt that the stages of organic evolution are 
correlated with and were actuated by the stages in the inorganic evolution 
of the earth itself. That climatic change was effective in inducing migra- 
tion, and thus in sharpening the struggle for existence against both enemy 
organisms and changed physical environment ; that extension and restric- 
tion of land and water areas in some cases brought about keener and more 
varied competition, change of habit or food, and in others the destruction 
of potential enemies and the securing of the advantages of a fair field for 
the survivors; and that activity of the earth-crust in such things as 
deposition and mountain-building provided conditions for the existence of 
an increased range of varieties and the consequent struggle between them. 
If we are not allowed to say that this brought about the survival of the 
fit, it at least caused the destruction of the unfit. 
2. It may be stated as a biological law that every locality becomes 
‘full’ of life, forms arriving or evolving to take advantage of the special 
facilities offered. In consequence, resistance to the incursion of new 
forms, even if they are exceptionally equipped, is very great, and it is 
only occasionally that such new forms can make good their immigration. 
There are, of course, marked exceptions, but these generally occur when 
degeneration or overgrowth in size accompanied by neglect of means of 
defence have occurred, or when an area has been for so long sheltered from 
the wider and more general course of evolution that it has fallen seriously 
behindhand in the race. 
The geological record gives indirect evidence of the same ‘ filling’ of 
areas in the past in the extraordinary slowness with which advanced types, 
that have eventually made great headway, established themselves after 
their introduction ; the earliest fishes, reptiles, and mammals are cases 
in point. Imperfect as the first members of these groups undoubtedly 
were, they must, even shortly after their introduction, have possessed 
considerable advantages over the older and established forms with which 
they found themselves in competition. In size and strength they were 
doubtless inferior, and probably they must have taken long periods to 
make good their advantage. But in all such cases the new forms went for 
a long period into ‘retreat,’ and, in face of the apparent slowness of their 
evolution and the bitter competition to which they were subjected, it is 
remarkable that they overpassed the troubles of racial youth, and 
eventually took the place to which they were entitled in the scheme of 
life. It seems justifiable to believe that there must have been at least 
some well-equipped types which did not survive competition in these early 
stages, but went under with all their promise of future success. We can 
easily imagine that the survival of such, had it occurred, may have altered 
the whole course of evolution and produced a life story very different from 
that we know to-day, and of which we ourselves form no small part. 
