94 



ing additional light upon this very interesting subject of in- 

 quiry ; but I have hitherto found it to be a rule that the 

 species of mollusca peculiar to great depths, are invariably 

 of a small size ; and that where the same species is met 

 with through a considerable range of depth, the individuals 

 inhabiting the deeper water are smaller. The depth at 

 which animal and vegetable life can exist must no doubt 

 be modified by the circumstances and conditions of the 

 ocean in various latitudes and localities ; and we accord- 

 ingly find, in the Norwegian seas, that the same or similar 

 species frequent much greater depths than they have been 

 known to do elsewhere, and this we might be naturally led 

 to expect, from the circumstance of the water being less 

 dense, and better adapted to the transmission of light. 



I can see no grounds for supposing the vast unfathomed 

 depths to be occupied by organic beings: analogy appears 

 to be against such supposition. We know that an elevation 

 of a very few miles above the earth's surface is unfavourable 

 to the life of animals and vegetables — not merely on account 

 of the lowness of temperature, but from the rarified state of 

 the atmosphere; and it appears to me not unreasonable to 

 infer, that a distance beneath the globe's surface, smaller in 

 the ratio of the increased density of the water, as a medium, 

 compared with air, would be equally unfavourable. It is 

 true, we are told by Mr. Scoresby, of a whale plunging to 

 the depth of 1000 fathoms ; but this appears less wonderful 

 when we consider the bulk of the animal ; it is but eighty or 

 one hundred times the length of its own body. From the 

 circumstance of his knocking his head against the bottom, it 

 would appear that he was bewildered when he got there ; and 

 the whale certainly procures his food and generally passes ihs 

 time much nearer the surface. The eagle and other birds 

 occasionally soar to an extraordinary altitude; and so there 

 may be middle depths in the ocean occasionally visited by 

 fishes, but never permanently inhabited by them. In a 



