366 POPULAR SCIENCE MONTHLY. 



there were no liiglilj developed brains social strategy of the more 

 oblique kind was uncalled for, just as hundred-ton guns were un- 

 called for before the days of ironclads. We know that the develop- 

 ment of the critical and plotting part of the brain is of compara- 

 tively 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 com- 

 paratively 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 care- 

 ful 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 w^hich 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 sufliciently 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. ISTow, 

 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 sj^arkling eye, and I think we shall find it in 



