THE PRINCIPLES OF BIOLOGY. 
135 
Subjected as every department of nature now is to the 
scrutiny of modern science, the fact of universal evolution 
could not much longer have remained undiscovered. 
Voltaire was once by all—and still is by some—theo¬ 
logians charged with atheism. Yet it was he who wisely 
asserted that were there no Creator, it would be necessary— 
in order to account for facts around us—“ to invent one !” 
In the same way, had we not in our vocabulary a word 
of sufficient expansiveness to cover the universe of mind as 
well as of matter, we should have to invent one. But as men’s 
minds, searching after truth, saw in every direction, not 
only in existing, but in geologic records of successive forms 
of life, change without disruption, it became more and more 
necessary to frame a formula which should express the order 
which reigns where previously it was thought that accident 
and chaos might be held accountable for all that happened. 
Thus the word “ Evolution” has been raised to a dignity 
rivalling that of “ Creator” in its universality. The applica¬ 
tion of the word “evolution” is, even by many students, limited 
to only a part of its full significance. An organ, by disuse, 
first loses its function, then the organ itself will in part or 
entirely disappear, according to its value in the general 
economy of the life of the animal or plant of which it forms 
a part. The partial or entire suppression of organs no longer 
required, or which are less necessary than previously, is 
clearly as much a part of evolution as is the development of 
entirely new organs either in substitution for or addition to 
existing organs. Further, what we call degradation even to 
extinction is still evolution. Death itself is necessary for the 
maintenance of life. So then the theory that high and 
complex forms of life are due to an innate desire on the part 
of low and simple forms to attain to something higher and 
more complex as presumably better is in no way substantiated 
by facts. Under prolonged domestication animals lose simul¬ 
taneously or successively those organs which in a state of 
perfect freedom and self-dependence are necessary for attack 
or defence against other animals or climatic rigour. 
The Shetland ponies wear more shaggy coats on their 
home hills than in this and other milder climes to which they 
are transported. Those animals which are reared in variable 
climates change their natural covering to suit the changed 
external temperature. So also do plants. The sheep in a 
wild state grows horns for combative purposes and conditions 
which do not exist under domestication. The hair-like wool 
of the wild sheep is better adapted to keep its body uniformly 
dry than is the absorptive covering which has been developed 
