OP PISHES. 51 



of equal density, the internal resistance would be in 

 proportion to weight placed over it ; but as they 

 do not correspond, in that respect, they would be 

 liable to the injuries and destruction, ficm the cause 

 that has been mentioned. 



Over the eye, the first investing membrane, the 

 conjunctiva of the human eye, is loose, and wrink- 

 led in fishes brought up from deep water, but 

 smooth and glossy on those at medium depths. 

 Does this not look like compressing the fluids into 

 smaller space ? It is certain that some aquatic 

 eyes cannot, by the nature of globular tunics, be 

 condensed, without rupturing them. But it is 

 needless to dwell on a subject, which, perhaps, is 

 already familiar to our readers. 



As it respects the power of vision under water, 

 we can only infer the principle, by our knowledge 

 of the laws of optics. That fishes see at great dis- 

 tances, is well established, but a turbid condition 

 of the water, renders vision indistinct, and hence 

 they are often deceived, and involved in fearful 

 difficulties. In clear, calm weather, they proba- 

 bly are able to discover objects much farther than 

 would at first be supposed, considering the medi- 

 um through which the light is transmitted. The 

 whale examines a boat one or two miles off, disi- 

 tinctly, and if enraged by the sting of a harpoon, 

 runs or swims with prodigious speed towards the 

 object that has excited its revenge. 



