The Theory of Natural Selection. 267 
other parts of that species may survive for any number 
of ages as they originally were. In the one case there 
is a ladder-like transmutation of species in time; in 
the other case a possibly tree-like multiplication of 
species in space. But whether the evolution of spe- 
cies be thus serial in time or divergent in space, the 
object of natural selection, so to speak, is in either 
case the same—namely, that of preserving all types 
which prove best suited to the conditions of their 
existence. 
Once more, the term “struggle for existence”? must 
be understood to comprehend, not only a competition 
for life among contemporary individuals of the same 
species, but likewise a struggle by all such individuals 
taken collectively for the continuance of their own 
specific type. Thus, on the one hand, while there is 
a perpetual civil war being waged between members 
of the same species, on the other hand there is a 
foreign war being waged by the species as a whole 
against its world as a whole. Hence it follows that 
natural selection does not secure survival of the fittest 
as regards individuals only, but also survival of the 
fittest as regards types. This is a most important 
point to remember, because, as a general rule, these 
two different causes produce exactly opposite effects. 
Success in the civil war, where each is fighting against 
all, is determined by zvdividual fitness and self-reliance. 
But success in the foreign war is determined by what 
may be termed ¢ridal fitness and matual dependence. 
For example, among social insects the struggle for 
existence is quite as great between different tribes or 
communities, as it is between different individuals of 
