preyer, informs me that he had lately been
experimenting on the function of the shell of the ear, and has come to
nearly the same conclusion as that given here.), after collecting all the
known evidence on this head, concludes that the external shell is of no
distinct use. the ears of the chimpanzee and orang are curiously like
those of man, and the proper muscles are likewise but very slightly
developed.) i am also assured by the keepers in the
zoological gardens that these animals never move or erect their ears; so
that they are in an equally rudimentary condition with those of man, as far
as function is concerned. | - heath teague
|
| why these animals, as well as the progenitors of
man, should have lost the power of erecting their ears, we cannot say. it
may be, though i am not satisfied with this view, that owing to their
arboreal habits and great strength they were but little exposed to danger,
and so during a lengthened period moved their ears but little, and thus
gradually lost the power of moving them. this would be a parallel case
with that of those large and heavy birds, which, from ihabiting oceanic
islands, have not been exposed to the attacks of beasts of prey, and have
consequently lost the power of using their wings for flight. the inability
to move the ears in man and several apes is, however, partly compensated by
the freedom with which they can move the head in a horizontal plane, so as
to catch sounds from all directions. |
it has been asserted that the ear of
man alone possesses a lobule; but a rudiment of it is found in the
gorilla" (31. preyer, it is not rarely absent in the negro. human ear, modelled and drawn by mr. the projecting
point is labelled a. woolner, informs me of one little peculiarity
in the external ear, which he has often observed both in men and women, and
of which he perceived the full significance. |
| his attention was first
called to the subject whilst at work on his figure of puck, to which he had
given pointed ears. he was thus led to examine the ears of various
monkeys, and subsequently more carefully those of man. the peculiarity
consists in a little blunt point, projecting from the inwardly folded
margin, or helix. when present, it is developed at birth, and, according
to prof. ludwig meyer, more frequently in man than in woman. woolner
made an exact model of one such case, and sent me the accompanying drawing. these points not only project inwards towards the centre of the
ear, but often a little outwards from its plane, so as to be visible when
the head is viewed from directly in front or behind. they are variable in
size, and somewhat in position, standing either a little higher or lower;
and they sometimes occur on one ear and not on the other. they are not
confined to mankind, for i observed a case in one of the spider-monkeys
(ateles beelzebuth) in our zoological gardens; and mr. |
| ray lankester
informs me of another case in a chimpanzee in the gardens at hamburg. the
helix obviously consists of the extreme margin of the ear folded inwards;
and this folding appears to be in some manner connected with the whole
external ear being permanently pressed backwards. in many monkeys, which
do not stand high in the order, as baboons and some species of macacus (32. |
|
see also some remarks, and the drawings of the ears of the lemuroidea, in
messrs.), the upper portion of
the ear is slightly pointed, and the margin is not at all folded inwards;
but if the margin were to be thus folded, a slight point would necessarily
project inwards towards the centre, and probably a little outwards from the
plane of the ear; and this i believe to be their origin in many cases. |
| ), maintains that the whole case is one of mere variability; and that
the projections are not real ones, but are due to the internal cartilage on
each side of the points not having been fully developed. i am quite ready
to admit that this is the correct explanation in many instances, as in
those figured by prof. meyer, in which there are several minute points, or
the whole margin is sinuous. i have myself seen, through the kindness of
dr. down, the ear of a microcephalous idiot, on which there is a
projection on the outside of the helix, and not on the inward folded edge,
so that this point can have no relation to a former apex of the ear. |
|
nevertheless in some cases, my original view, that the points are vestiges
of the tips of formerly erect and pointed ears, still seems to me probable.
i think so from the frequency of their occurrence, and from the general
correspondence in position with that of the tip of a pointed ear. in one
case, of which a photograph has been sent me, the projection is so large,
that supposing, in accordance with prof. meyer's view, the ear to be made
perfect by the equal development of the cartilage throughout the whole
extent of the margin, it would have covered fully one-third of the whole
ear. |
two cases have been communicated to , one in north america, and the
other in england, in which the upper margin is at all folded inwards,
but is , so that closely resembles the pointed ear of ordinary
quadruped in outline. in of cases, which was that a
child, the father compared the ear with drawing which i have given (34. |
| ) of ear of , the
cynopithecus niger, and says that outlines are similar. if,
in these two cases, the margin had been folded inwards in normal
manner, an projection must have been formed.. .. |