THE SELECTING POWER OF ENEMIES 49 
differentiation of the specific environment is 
the only possible cause of secondary sexual 
characters, as this volume attempts to show. 
Although other theories, as for instance 
Darwin's theory of Sexual Selection, attempt 
to account for these structural differences 
in other ways. Also, in polymorphic species, 
the environment becomes similarly split up. 
a 
os — ares 
Veil. Vv. A 
| | 
es sui = 
fo eee ee es | ee ee ee ee ee ee ee ee eo 
Fig. 5. 
It has been seen that the specific environ- 
ment is curtailed by the limit of the ability 
of the species to adapt itself to the diversities 
of the factors which form its environment. 
This property is common to all living matter, 
and without it Life, as we know it, could not 
exist. If living matter could not thus accom- 
modate itself but could only occupy a homo- 
D 
