THE PSYCHOLOGICAL LABORATORY AT HARVARD. 403 
a circular motion. Hanging out into 
the tubes, from their sides, are hairs or 
cilia, which connect with nerve cells 
and fibres that branch off from the 
auditory .nerve. When the head moves 
the fluid moves, the hairs move, the 
cells are “fired off,’’ a nervous current 
is sent up to the brain, and a feeling 
of the head’s peculiar motion is con¬ 
sequent. 
As for seasickness : this nerve cur¬ 
rent, on its way to the brain, at one 
point runs beside the spot or “centre” 
f'here-the nerve governing the stomach 
as its origin. When the rocking of 
the head is abnormally violent and 
prolonged, the stimulus is so great that 
the current, leaks over into this ad¬ 
joining “centre,” and so excites the 
nerve running to the stomach as to 
cause wretchedness and retching. 
Deaf mutes, whose ear “ canals ” are 
affected, are never seasick. 
But normally the amount of ear¬ 
feeling which we get by reason of 
moving our head in a particular direc¬ 
tion comes in a' curious way to be a 
measure of the direction of sound. 
The feelings we get from our skin and 
muscles in turning the head play a 
similar rôle. We turn our ear to catch 
a sound. We do this so frequently for 
every point, that in time we learn to 
judge the direction of the sound by 
the way we would have to turn the 
head in order to hear the sound best. 
Thereafter we do not have to turn the 
head to get the direction, for we now 
remember the proper feeling and know 
it. This memory of the old feeling is 
our idea of the present direction. If 
we never moved our heads we never 
could have any such notion of the 
location of sounds as at present—per¬ 
haps none whatever. 
MENTAL ORIGIN OF NUMBERS. 
Number ! surely there can be noth¬ 
ing mysterious here ; no “ law ” to be 
discovered about one, two, three ? 
Well, the next time you shake hands, 
ask the man what he feels. A hand. 
Then ask further and he will feel five 
fingers. Now ask‘ rightly and he will 
feel any number of distinct spots of 
pressure. But the real pressures were 
practically the same all through. Why, 
then, did . he feel first one, then five, 
then eight, ten, or a dozen ? So with 
the objects we become acquainted with 
through any of our senses ! Why does 
the same bit of nature now stand 
before us “ one tree,” and now a myriad 
of leaves and branches ? Why do the 
same outer groupings fall into such 
different inner groupings ? Why does 
not the result of each little nerve of 
the millions continually played on in 
eye, ear, and skin stand out by itself, 
and we have so many million feelings ? 
To explain this : the first time a 
child opens his eyes he sees, as Profes¬ 
sor James says, but “one big, bloom¬ 
ing, buzzing confusion.” Not till some 
“ whole” (knife) be broken up into parts 
(blade, handle) and each part be men¬ 
tally perceived in immediate succession 
the one after the other can the idea of 
“ twoness ” ever be possible to that 
child. The “ twoness ” is a feeling of 
distinct nature apart from thé two 
terms (blade, handle). It rises from 
the “ shock of succession.” It is one of 
the “ modified states ’’’wrought by one 
element on another, which we studied 
in our first experiment. Once lodged 
in the mind, the feeling may be re¬ 
membered and reawakened, like any 
other. Thereafter the two parts or 
terms may come before the mind, 
awaken this feeling of twoness, and now 
stand side by side, simultaneously and 
numerically separate. 
These are the primary laws of num¬ 
ber perception. Our experiments illus¬ 
trate and prove them. Though the 
nerves lying under a needle point are 
really several in number, the pressure 
on them is commonly felt as “ one 
prick.” The area is so small that 
usually, through life, all the nerves 
have been pressed together. They 
have not been split up and pressed 
enough times in succession among 
themselves for a memory of “ twoness ” 
to have been developed among them. 
But, by proper manipulation, not un¬ 
like some of the processes of hypno¬ 
tism, yet perfectly normal, the “two¬ 
ness” of some other group of nerves 
can be yoked to the feeling resulting 
from the pressure of a particular nee-, 
die point. Thereupon the one needle