THE EVOLUTION OF ORGANIC BEHAVIOUR 35 
the brain is the organ of conscious control, granting that it 
can receive impulses from and transmit impulses to the reflex 
centres, no more is here implied, and no more can be legiti- 
mately inferred, than that the kind of organic behaviour we 
call “reflex action” is in the higher animals in touch with 
the guiding centres. We have no ground for assuming that 
in reflex action there is any power of intelligent guidance 
independent of that which is exercised by the brain or 
analogous organ. In brief, reflex acts, in animals endowed 
with intelligence, may be regarded as specialized modes of 
organic behaviour; which are in themselves often charac- 
terized by much complexity ; which subserve definite biological 
ends; which are effected by subordinate centres capable of 
transmitting impulses to, and receiving impulses from, the 
centres of intelligent guidance ; and which, as responses con- 
fined to certain organs or parts of the body, form elements 
in the wider behaviour of the animal as a whole. 
VI.—TueE Evouution oF ORGANIC BEHAVIOUR 
The interpretation of organic behaviour in terms of evolu- 
tion mainly depends on the answer we give to the question : 
Are acquired modes of behaviour inherited? A negative 
answer to this question is here provisionally accepted. But 
the premisses from which this conclusion is drawn are too 
technical for discussion in these pages. It must suffice to 
state as briefly as possible what this conclusion amounts to, 
and to indicate some of the consequences which follow from 
its acceptance. 
The fertilized, erg gives origin, as we have seen, to the 
multitude of cells which build up the body of one of the 
higher animals. There are, on the one hand, muscle-cells, 
gland-cells, nerve-cells, and other constituents of the various 
tissues ; and there are, on the other hand, the reproductive 
cells—ova or sperms, as the case may be. Now, every cell in 
the developed animal is a direct descendant of the fertilized 
egg, But of all the varied host only the reproductive cells 
