122 
E. M. CAMPBELL—ON INSTINCT. 
by the mental element, it is undistinguishable from a reflex act, 
which is frequently performed by all members of the same species. 
If it be so modified, it is undistinguishable from reason. This 
observation is perfectly reconcileable with a general acceptance 
of the theoretical definition given by this distinguished writer. 
Psychology necessarily admits of a greater use of subjectivity than 
is required by an observer of natural phenomena; indeed the less 
of this he introduces into the object under contemplation, the 
nearer he will be to truth. Before entering further into this 
matter, I will touch briefly on reflex action, for I fear that u non¬ 
mental neuro-muscular adjustment ” may not be an intelligible 
definition to some of our members. 
We may conveniently confine the term Beflex Action to animals 
which possess nerves and muscles, although the phenomena ex¬ 
hibited by such sensitive plants as Venus’ fly-trap and the sensitive 
Mimosa differ in hardly any respect from reflex action, for we 
have in these—an acting stimulus, a latent period, and a response in 
the form, of movement—phenomena which cannot be distinguished 
from reflex action. In all reflex action there is an exciting cause 
and a movement, as well as a constant relation between the two 
which has been established by the individual itself or by its 
ancestors. I am aware that secretion is regarded by some as a 
reflex action, but bearing in mind the present state of science, and 
for the sake of simplicity, I have excluded cases of secretion. Had 
I chosen to include them, they would not have modified my con¬ 
clusions, though they might have led me to widen the definition 
of reflex action. A sucker of a limb of an octopus which is 
separated from the body will adhere to a solid substance through 
the action of its own nerve-ganglion .^ 4 The same principle is in¬ 
volved when a man who is so paralysed that he has no feeling in 
his legs, moves them when his feet are tickled. 
Our own experience tells us how easily some actions acquired with 
much difficulty come to be performed unconsciously after having 
been often repeated. Such acts frequently take place as the result 
of some occurrence which has habitually preceded them. We may 
walk about the room deep in thought, when suddenly we stop and 
find immediately in front of us a chair with which another step 
would have brought us into collision; yet when we stopped we 
were quite unconscious of anything being in our way. There was, 
in fact, an established relation between an object before us, the 
optic nerve, and the mechanism employed in arresting our move¬ 
ment. An impulse was carried by the optic nerve to a nerve centre 
or centres, and was there transmuted into fresh impulsions along the 
nerves in connection with the numerous muscles used in our action of 
stopping. The optic nerve had so frequently received similar im¬ 
pulses, and conveyed them to its nerve-centre, that the latter knew 
what to do with them without appealing for direction to a higher con¬ 
trolling power, viz. a higher nerve-centre. The limits of my paper pre¬ 
vent me from entering into the many forms and the combinations of 
* See H. Spencer’s ‘ Principles of Psychology,’ p. 428. 
