276 JOURNAL OF COMPARATIVE NEUROLOGY. 
functions may be regarded as developed ultimately for the sake 
of this process of manipulation and ingestion. Taste, smell, 
the static sense, hearing and sight, can all be shown to have 
been developed for the sake of perceiving the distant food or 
sex object. And locomotion is instrumental to the same end. 
The leg was developed for the sake of the jaw, not the jaw for 
the sake of the leg. All these successive developments of or- 
gans are more or less plainly designed to mediate the act of 
bringing the distant object to the mouth—or, at least, to medi- 
ate the manipulation of it in such a way as, sooner or later, to 
bring about gratification of some sort._ 
Thus we have seen how in and through the attempt to 
solve great life problems the evolving animal form has gradually 
extended the sphere of its activity by means of the develop- 
ment of organs both sensory and motor for relating it in a larger 
environment. As Lorze has pointed out, when a person takes 
a stick in his hand to feel his way in the dark he thereby en- 
larges his immediate tactual or contact environment by the 
length of the stick itself, or, looking at it from the other side, 
he thereby enlarges his own personality, his own organism. So 
with the telescope or microscope: they are but extensions of 
the eye. The steam-hammer and sewing-machine and reaper 
are extensions of the hand. The locomotive, bicycle, ship, 
aerodrome are extensions of the leg or wing. It is the first — 
great upward step in the evolution of consciousness when the 
animal begins to state its environment in terms of its own activ- 
ity. The space and time worlds represent simply the attempt 
of the animal to state in the form of practically useful equations 
the mutual relations between the tactual, the visual and the 
kinaesthetic imagery. 
Vassar College. 
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