Page:Popular Science Monthly Volume 53.djvu/382

366 there were no highly developed brains social strategy of the more oblique kind was uncalled for, just as hundred-ton guns were uncalled for before the days of ironclads. We know that the development of the critical and plotting part of the brain is of comparatively recent date, but that the mechanism of the emotions and the more automatic mental processes is extremely ancient. Hence the surviving methods of communication which belonged to the earlier ages, and are closely connected with the machinery of emotion, do not so readily lend themselves to civilized mental artifices as the comparatively new-fangled organs of speech. They are to a great extent independent of the conscious will. I shall endeavor to explain, when discussing the physiology of ocular expression, how it is that the eyes maintain their pristine simplicity and often betray the lying tongue.

In his treatise on the Anatomy of Expression, Sir Charles Bell draws attention to the fact that the changes which take place in the appearance of the eye are due chiefly to the surrounding structures, and not to alterations in the eyeball itself. When, therefore, one is discussing the causes of ocular expression, it is necessary to take account of the muscles of the brow and also of those which surround the orbit. I think, however, that the eyeball per se undergoes more change under the influence of emotion than has been supposed. It has been said that the glistening or sparkling of the eye is simply the result of the ball being compressed from the outside; but careful experiments seem to show that the orbicular and other muscles surrounding the eyeball have less constricting power than they have received credit for. One finds, both in man and in animals, that the eye is capable of sustaining a good deal of pressure from the front without any marked change in its general aspect. Any one who has observed the large cushion of fat which lines the roomy orbit, and which forms a soft bed for the ball, will understand how easily the eye evades pressure from the orbicular muscle. Of course, if all the little muscular straps which proceed from the back of the orbit, and are attached to the sclerotic, were to contract vigorously at the same time, ocular tension might be sufficiently increased to cause the front surface to be tight and glistening. But it will be plain to every anatomist that if this took place the eye would be completely disorganized as a visual apparatus, because the distance between the lens and retina would be so increased as to throw the focusing machinery completely out of gear. The effect of pressure so applied would be to make the eye extremely short-sighted. Now, it is quite possible to have the eye sparkling with emotion and yet retain the normal powers of sight. We must look elsewhere for the mechanism of the sparkling eye, and I think we shall find it in