The senses are those special organisms that connect us with the outer world through which external impressions are received and transmitted to the brain—the great sensorium or centre of the nervous system. They are popularly designated as sight, hearing, smelling, touch, and taste, each having its own peculiar organism; some, as sight, exceedingly elaborate, and others, like taste, quite simple, being little more than a delicate expansion of nervous matter spread upon the tongue and lining the inner surface of the mouth. The nervous system includes the brain and the nerves, but is, in fact, an indivisible whole, of which the brain forms the centre, and the nerves the circumference, in exact proportion as we ascend in the scale of being. The centre of the nervous system is increased and the circumference diminished as the brain becomes larger and the nerves smaller. Among quadrupeds—the horse, for example—the nerves are enormously large in comparison with the brain of that animal; and this holds good throughout, so that an intelligent physiologist might determine the possible capabilities of any of the higher order of animals by a simple comparison of the brain and nerves. And in the human creation a single skull of a Mongol, or Malay, or Negro, and especially of the latter, should be quite sufficient to enable a physiologist to comprehend the essential character of the race to which it belonged. True, he might, as has often happened, mistake it for an abnormal specimen of the Caucasian, and thus display a vast amount of learned nonsense of the Gall-Spurzheim order, but if he knew it to be an actual negro skull, and then compared it with that of the Caucasian, he should be able not only to determine the intellectual inferiority, but the vastly preponderating sensualism of the former. He would see that the relatively small cerebrum, and the large cerebellum, must be united with a corresponding development of the senses, and a comparatively dominating sensualism. The mere organism of the senses, of sight, hearing, etc., though of course differing widely from those of the Caucasian, it is not necessary to describe, for even in animals of the higher class there is a certain resemblance, and the student of anatomy studies the mechanism of the eye in the ox or horse as satisfactorily as in that of the human creature.