In behavior the individuals of these two groups differed
strikingly. Those of the first group danced frequently,
violently, and in a variety of ways; they seldom climbed
on a vertical surface and when forced to move on an
incline they usually descended by sliding down backwards
or sidewise instead of turning around and coming down
head first; they gave no signs whatever of hearing
sounds. Those of the second group, on the contrary,
danced very moderately and in few ways; they climbed
the vertical walls of their cage readily and willingly,
and when descending from a height they usually turned
around and came down head first; two of the four evidently
heard certain sounds very well. No wonder that
Cyon suggests the possibility of a different origin!
It seems not improbable that the individuals of the
second group were of mixed blood, possibly the result
of crosses with common mice.
As I shall hope to make clear in a subsequent discussion
of the dancer’s peculiarities of behavior, in
a chapter on individual differences, there is no sufficient
reason for doubting the general truth of Cyon’s
description, although there is abundant evidence of
his inaccuracy in details. If, for the present,
we accept without further evidence the statement that
there is more than one variety of dancer, we shall
be able to account for many of the apparent inaccuracies
of description which are to be found in the literature
on the animal.
As a result of the examination of the facts which
this chapter presents we have discovered at least
six important peculiarities of behavior of the dancer
which demand an explanation in terms of structure.
These are: (1) the dance movements—whirling,
circling, figure-eights, zigzags; (2) restlessness
and the quick, jerky movements of the head; (3) lack
of responsiveness to sounds; (4) more or less pronounced
deficiency in orientational and equilibrational power;
(5) lack of visual dizziness; (6) lack of rotational
dizziness.
Naturally enough, biologists from the first appearance
of the dancing mouse in Europe have been deeply interested
in what we usually speak of as the causes of these
peculiarities of behavior. As a result, the structure
of those portions of the body which are supposed to
have to do with the control of movement, with the
phenomena of dizziness, and with the ability to respond
to sounds, have been studied thoroughly. In the
next chapter we shall examine such facts of structure
as have been discovered and attempt to correlate them
with the facts of behavior.
CHAPTER V
STRUCTURAL PECULIARITIES AND BEHAVIOR
The activities of an animal are expressions of changes
which occur in its structure, and they can be explained
satisfactorily only when the facts of structure are
known. Such peculiarities of activity as are exhibited
by the dancing mouse, as contrasted with the common
mouse, suggest at once that this creature has a body
which differs in important respects from that of the
ordinary mouse. In this chapter I shall present
what is known concerning the structural bases for
the whirling, the lack of equilibrational ability
and of dizziness, the quick jerky head movements,
the restlessness, and the partial or total deafness
of the dancing mouse.
Copyrights
The Dancing Mouse from Project Gutenberg. Public domain.
