Some of us remember Sally, the chimpanzee at the "Zoo" with which Dr.
Romanes used to experiment. She was taught to give her teacher the
number of straws he asked for, and she soon learned to do so up to five.
If she handed a number not asked for, her offer was refused; if she gave
the proper number, she got a piece of fruit. If she was asked for five
straws, she picked them up individually and placed them in her mouth,
and when she had gathered five she presented them together in her hand.
Attempts to teach her to give six to ten straws were not very
successful. For Sally "above six" meant "many," and besides, her limits
of patience were probably less than her range of computation. This was
hinted at by the highly interesting circumstance that when dealing with
numbers above five she very frequently doubled over a straw so as to
make it present two ends and thus appear as two straws. The doubling of
the straw looked like an intelligent device to save time, and it was
persistently resorted to in spite of the fact that her teacher always
refused to accept a doubled straw as equivalent to two straws. Here we
get a glimpse of something beyond the mere association of a
sound--"Five"--and that number of straws.