94 SECTIONAL ADDRESSES 
We find very often that a simple directive activity is part of a general 
directive process of long range, which may take months to reach its goal ; 
and to understand the simple action we must relate it to, or integrate it 
in, the general process of which it is a part. Take for instance the 
building of a nest by a bird. This taken by itself is a directive activity, 
aimed at the construction and completion of an adequate brooding place 
for the eggs and young. It is a fairly stereotyped and specific activity, but 
unusual materials may be pressed into service if the normal materials are . 
hard to come by. But nest-building is simply one link in the long re- 
productive cycle, which may commence with migration, and its relation 
to that cycle, which includes both behavioural and physiological activities, 
must be studied if we are to understand it fully. 
This illustrates the general rule of biological method which we have 
just discussed—that the whole life-cycle of activity must be regarded as 
the primary thing, and that the parts of it which may be isolated for study 
must be re-integrated in the whole-activity. ‘The human mind is prone 
to analysis, and we must be on our guard against its inveterate tendency 
to separate and distinguish parts or elements in what are, fundamentally, 
continuous processes. 
In thus relating partial events to life-cycle, we must of course consider 
above all their time-relations, not only their relations to what has gone 
before, but also and more particularly to what follows after. I should 
like to refer in this connection to a recent address by Coghill, in which 
the organismal view of development, including the development of 
behaviour, is set out with great clearness and authority. He tells us that 
“the neuro-embryologic study of behavior shows that events within a 
behavioral system can be understood scientifically only as their relation 
is known to subsequent as well as to antecedent phases of the cycle. The 
antecedent tells a part of the story about the present, but not all of it ; for 
within the present are events that have behavioral significance only in 
that which follows. ... The purely scientific method, dealing ex- 
clusively as it does with space-time relations, can not reject the future 
from its explanation of the present in behavior, because any event in an 
organismic cyclic system is an integral part of both the future and the 
past.’ ? 
We come now to the question, how is behaviour instigated or initiated, 
how is it set going? ‘There is one ready-made answer to this question— 
that behaviour is essentially an automatic response or reaction to stimula- 
tion, either external or internal. You will recall the passage I quoted 
from Pavlov earlier in this address, in which the stimulus-response theory 
is very clearly and explicitly set forth. According to Pavlov, stimulus is 
related to reaction as cause to effect; the impulse generated by the 
stimulation of the receptor organ is automatically transmitted along the 
appropriate nervous pathways to set in motion the appropriate effector 
organ. Behaviour is therefore completely determined by the stimuli 
7 G. E. Coghill, ‘The Neuro-embryologic Study of Behavior: Principles, 
Perspective and Aim.’ Science, 1xxviii, 1933, pp. 137-138. I have expressed a 
similar view in my Interpretation of Development and Heredity, 1930, pp. 170-171. 
