26 Evolution and Adaptation 
to the destruction of the young, is manifestly disadvantageous 
to the race. As soon, however, as we enter the field of so- 
called abnormal developments, the adaptive relation of the 
organism to its environment is very obscure; and yet, as in 
the case of adaptation to poisons, we see that we cannot draw 
any sharp line between what we call normal and what we call 
abnormal development. 
COMPARISON WITH INORGANIC PHENOMENA 
The preceding examples and discussion give some idea of 
what is meant by adaptation in living things. In what respects, 
it may be asked, do these adaptations differ from inorganic 
phenomena? The first group of inorganic bodies that chal- 
lenges comparison are machines. These are so constructed 
that they may be said to accomplish a definite purpose, and 
the question arises whether this purpose can be profitably 
compared with the purposefulness of the structure and 
response of organisms. That the two cannot be profitably 
compared is seen at once, when we recall the fact that the 
activity of the machine is of no use to it, in the sense of 
preserving its integrity. The object of the machine is, in 
fact, to perform some useful purpose for the organism that 
built it, namely, for man. Furthermore, the activity of the 
machine only serves to wear it out, and, therefore, its actions 
do not assist in preserving its integrity as do some, at least, 
of the activities of an animal. It is true, of course, that in a 
mechanical sense every action of the organism leads also to a 
breaking down of its structure in the same way that a machine 
is also worn out by use; but the organism possesses another 
property that is absent in the machine, namely, the power of 
repairing the loss that it sustains. 
One of the most characteristic features of the organism is: 
its power of self-adjustment, or of regulation, by which it 
adapts itself to changes in the environment in such a way 
