The functions of the ear as at present known to the
comparative physiologist are grouped as the acoustic
and the non-acoustic. The cochlea is supposed
on very good grounds to have to do with the acoustic
functions, and the organs of the semicircular canals
on equally good evidence are thought to have to do
with such of the non-acoustic functions as equilibration
and orientation. Just what the functions of the
organs of the ear sacs are is not certainly known.
These facts are of importance when we consider the
attempts made by Alexander and Kreidl to correlate
the various peculiarities of behavior shown by the
dancer with the structural facts which their work
has revealed. This correlation is indicated schematically
below. The physiological facts to be accounted
for in terms of structure are presented in the first
column, and the anatomical facts which are thought
to be explanatory, in the second (2 p. 539).
1 Lack of sensitiveness to auditory stimuli. {Structure
1,2,3 below}
2 Defective equilibrational ability. {Structure 4,5,6
below}
3 Lack of turning dizziness. {Structure 4,5,6 below}
4 Normal reactions to galvanic stimulation. (not related
in table to any Structure)
1 Destruction of the papilla basilaris cochleae, etc.
2 Diminution of the inferior branch of the eighth
nerve.
3 Marked degeneration of the ganglion spirale.
4 Destruction of the macula sacculi.
5 Diminution of the branches and roots of the superior
and middle branches of the eighth nerve.
6 Diminution of both ganglia vestibulii and of the
nerve cells.
Alexander and Kreidl themselves believe that the partial
deafness of the dancers (for they admit that the total
lack of hearing has not been satisfactorily proved)
is due to the defective condition of the cochlea.
They account for the imperfect equilibrational ability
of the animals by pointing out the structural peculiarities
of the sacculus, the vestibular ganglia, and the peripheral
nerves. Similarly, the lack of dizziness they
suppose to be due to the diminution of the fibers of
the nerves which supply the canal organs, the atrophied
condition of the vestibular ganglia, and a disturbance
of the peripheral sense organs. Furthermore,
there are no anatomical facts which would indicate
a lack of galvanic dizziness (2 p. 552).
Despite the fact that they seem to explain all the
functional peculiarities of the dancer, the statements
made by Alexander and Kreidl are neither satisfying
nor convincing. Their statements concerning the
structure of the ear have not been verified by other
investigators, and their correlation of structural
with functional facts lacks an experimental basis.
