OCR Text |
Show 308 MR. H. M . W A L L I S O N T H E G R O W T H [Mar. 2, are neither abundant nor easy to examine. Their ears seem subject to much variation. M a n alone exhibits in infancy and reproduces in later life the ancestral hairy coat of the ear-a fact from which we may perhaps infer that at one time his ears had sufficient lateral projection to need other and more constant protection from the weather than the hair of the scalp afforded. The shape of the head of our ancestor who had pointed ears is not known, but it is highly improbable that his skull was of the lofty, domed, Caucasian type. If it were long and low, somewhat after the style of the Eocene Adapts, the ears would be set much higher in the head than ours, and would get no protection from any hair growing upon the scalp. Several contributary pieces of evidence suggest that the external ear is an organ diminished by disuse. Thus, it is no longer functional ; it varies extremely and constantly in shape and size and in other particulars. It is by its position exposed to sunburn, frostbite, and injuries of all kinds, yet it is ill-supplied with nerves of sensation and has a poor supply of blood. Consequently it heals slowly wffien cut. One might compare our external ear to an outpost once important, but now no longer essential, from which the garrison is withdrawing. M y friend Dr. Hurry, of Reading, points out that the hairs on the ears of both dark-haired and red-haired persons, already referred to, are lighter than the general tone of the hair of the head and cheeks. H e suggests that this may result from some deficiency of colouring-matter, which is in itself one process of degeneration. I have, however, too little evidence on this point to warrant m y doiug more than indicating a line worthy of further enquiry. But evidences of degeneration are, for the purposes of this enquiry, negative testimony ; let us seek for something positive as a clue to ancestral shape and size. The most puzzling feature seems to be the abrupt countermarch of the hairs upon the back of the helix. N o anthropoid or other quadrumanous animal, so far as m y limited observations extend, shows anything analogous. The arrangement is useless, is nob ornamental, but is so persistent that one is driven to believe that its history, if decipherable, would throw light upon the condition of the organ in past times. The theory which I propound upon this growth is submitted with extreme diffidence. This countermarch is in its incipience simply a divergence or radiation of the lines of growth of the hair, such as is found upon all funnel-shaped hairy ears where the diameter increases outwards from a short tubular concha to a larger expansion. This radiation is found among the hairs on the back of the human ear, the growth starting spirally at the junction of the head and concha, and diverging outwards, some to the one side of Darwin's Point, some to the ofc her (see Plate X I X . figs. 2 & 3). |