ected signs of other Cheyennes and
Sioux differ, not only from those on the reservation, but among
each other. Therefore the signs used in common by the tribes at
the reservation seem to have been modified and to a certain extent
unified.

The result of the collation and analysis of the large number of signs
collected is that in numerous instances there is an entire discrepancy
between the signs made by different bodies of Indians to express
the same idea, and that if any of these are regarded as rigidly
determinate, or even conventional with a limited range, and used
without further devices, they will fail in conveying the desired
impression to any one unskilled in gesture as an art, who had not
formed the same precise conception or been instructed in the arbitrary
motion. Few of the gestures that are found in current use are, in
their origin, conventional. They are only portions, more or less
elaborate, of obvious natural pantomime, and those proving efficient
to convey most successfully at any time the several ideas became
the most widely adopted, liable, however, to be superseded by more
appropriate conceptions and delineations. The skill of any tribe and
the copiousness of its signs are proportioned first to the necessity
for their use, and secondly to the accidental ability of the
individuals in it who act as custodians and teachers, so that the
several tribes at different times vary in their degree of proficiency,
and therefore both the precise mode of semiotic expression and the
amount of its general use are always fluctuating. Sign language as a
product of evolution has been developed rather than invented, and yet
it seems probable that each of the separate signs, like the several
steps that lead to any true invention, had a definite origin arising
out of some appropriate occasion, and the same sign may in this
manner have had many independent origins due to identity in the
circumstances, or if lost, may have been reproduced.

The process is precisely the same as that observed among deaf-mutes.
One of those unfortunate persons, living with his speaking relatives,
may invent signs which the latter are taught to understand, though
strangers sometimes will not, because they may be by no means the
fittest expressions. Should a dozen or more deaf-mutes, possessed
only of such crude signs, come together, they will be able at first to
communicate only on a few common subjects, but the number of those and
the genera