On the Anatomy and Physiology of the Organs of the Senses. 213 



are those of sensation. The fifth, the reproductive, have been made to 

 comprehend organic development and decay. 



The sensorial may then be regarded as superadded upon the other func- 

 tions, and not at all times necessary to the existence of life. 



Upon the importance of comparative anatomy, that is to say, of com- 

 paring the structure of the lower animals with that of the human frame, it 

 is unnecessary to insist. The organisation of man bears so many relations, 

 and presents so many analogies, to that of other animals, that the advan- 

 tages of a comparison must be obvious. 



And this is particularly true with regard to the senses. Of the vital 

 organs, those possessed by man are for the most part superior to all others, 

 but his sensorial are not, Man is inferior in keenness of vision to the 

 bird of prey, in acuteness of scent and hearing to the dog, in tact to the 

 bat J so that, althougli there does not appear to be any animal possessing 

 all the senses in a superior degree of perfection to man, yet as many of 

 them are superior to him upon a single sense, the parts of their organs are 

 larger and more fully developed, and are therefore better fitted for the 

 purposes of anatomical investigation. 



Again, as the sensorial organs of the animal are fitted to the medium in 

 which he lives, or the circumstances under which they are employed ; as 

 in the fish to water, in the bird to air, or in the night-prowling animals to 

 a small degree of light; we might in each of such cases expect to find some 

 part peculiarly prominent, and hence be enabled to draw some conclusion 

 as to its use. 



Thus, in the inner angle of the human eye we find a small eminence and 

 fold of membrane, upon the use of which we might in vain speculate ; but 

 we examine the eyes of the inferior animals, and there we find this fold 

 fully developed as a third eyelid ; a membrane, by the intervention of 

 which, the eagle is enabled to look at the sun. 



The consideration of the organs of the senses derives also great interest 

 from the close connexion subsisting between their functions and those of 

 the sensorium, in the reciprocating actions of either ; and the prospect 

 thence opened, of being enabled to comprehend something of a class of 

 phaenomena hitherto regarded as inscrutable. At any rate, the connexion 

 between the organs of the senses and the intellectual functions is evidently 

 extremely close ; so that it is difficult thoroughly to investigate the one, 

 without being led to bestow a good deal of attention upon the other. 



These organs are undoubtedly the parts of the material frame most con- 

 versant with its immaterial principle, they are tlie channels through which 

 much of our knowledge flows; music, as has been observed, has no charms 

 for the deaf, nor has painting for the blind ; and all the splendid imagery, 

 borrowed by the poet from the world without, would lose its magic power, 

 and might as well be presented to a marble statue as to man, were it not 

 for his senses. 



No. 4.— Vol. I. 2 G 



