264 JouRNAL OF COMPARATIVE NEUROLOGY. 
nations, fixed ideas, and motor types, where one sense seems 
to carry everything before it or where one type of imagery 
comes to predominate, as in the so-called visuels, audiles, and 
moteurs. In the normal organism this competition results in a 
balance or, where there is call for the successive action of dif- 
ferent functions, there will be set up a rhythmic alternation of 
the focus of attention from one to another of these centres of 
adaptation. 
The conception is not, let it be noticed, that consciousness 
is the invariable accompaniment of all motion or movement, 
but that consciousness is the accompaniment or product of rela- 
tive tension’ in adaptation—ve/ative tension, because the resist- 
ance which will be sufficient to produce consciousness under 
one set of circumstances will not be sufficient under another set 
of circumstances. If I am living with the roar of Niagara inmy 
ears, the sound of the rippling brook will elicit no consciousness, 
But if I am strolling through the silent forest, this sound will 
" attract my attention at once. Stated generally, tension is the 
condition of consciousness. What quality and quantity of ten- 
sion will be required, will depend upon the situation. 
Now, in the lowest organisms these conditions of tension 
must, of course, be very simple and the range of alternative 
means which can be utilized in the attaining of an end must be 
exceedingly limited. Contrast the problems which present 
themselves to the coral polyp with the problems that are in- 
volved in the adjustment of a mammal in its environment. The 
environment of the former is relatively homogeneous; the en- 
vironment of the latter is constantly shifting, not alone by rea- 
son of an inherent evolution of the environment, but also by 
reason of the constant change of scene which is brought about 
by the voluntary movements of the animal itself. Or contrast 
the hunger of an oyster with the hunger of a man, and the 
simplicity of the means employed to satisfy this craving in the 
one case with the complexity of the means used in the other. 
1<Or relative equilibrium,” which is the same thing (cf. HERRICK, Journ. 
of Compar. Neurol., VII, 155). 
