FISHES. 217 



prey of fishes is seized by the mouth, and retained there until 

 swallowed; and as the mouth at the same time admits the 

 stream of water to the gills, hut little mastication can possihly 

 take place; there is, consequently, hut little exercise of the 

 sense of taste. Its existence is, however, indicated in some 

 species both by the structure of the skin which covers the 

 palate, and by the supply of nerves. 



The sense of smell would appear to be enjoyed in great 

 perfection, not only from the development of the olfactory 

 nerves, but also from observations respecting habits. Mr. 

 Jesse states of fish which he kept in a pond suitable for the 

 purpose, that they preferred paste arid worms that had been 

 prepared by particular perfumes. 



The existence of the sense of hearing in fishes has been 

 questioned ere now, because there is no external organ ana- 

 logous to an ear. But the pleasing writer just quoted informs 

 us, that he has seen fishes suddenly move at the report of a 

 gun, though it was impossible for them to see the flash;* and 

 we know that the Chinese summon their Gold-fish to their 

 food by the sound of a whistle. The researches of the ana- 

 tomist would, however, be sufficient of themselves to remove 

 such a doubt, if it were ever seriously entertained. He reveals 

 to us the existence of a special apparatus for the purpose, 

 presenting great diversity in its arrangement; and we learn 

 that in cases such as those just mentioned, the sonorous 

 vibrations of the water were communicated to the organ of 

 hearing through the medium of the solid parts of the body. 

 In many species there is a communication between the ear and 

 the air-bladder; and it has hence been inferred that the air- 

 bladder, among other uses, serves to increase the intensity of 

 the undulations communicated through water to the body of 

 the fish.f With the parts of the auditory apparatus, called 

 the otolites, or ear-bones, every one is familiar. 



The sense of sight exists in great perfection; but the lenses 

 of the eye are modified to suit the denser medium through 

 which the rays of light must pass. In general, the eye is 

 much rounded, and the pupil is large, so as to allow the 

 greatest possible quantity of light to enter. But while such 

 careful arrangements are made for the sense of vision, in all 

 cases where that power can be exerted, the economy of nature, 



* Gleanings in Natural History, p. 74. 



t Miiller, quoted in Owen's Lectures, p. 211. 



