Vn!. 



59."'] PROCEEDINGS OF THE NATIONAL MUSEUM. 223 



great currents have little or nothing to fear from the mechanical attri- 

 tion which plays so large a part in the shallows. On the other hand, 

 wherever the force of the stream is not sufficient to sweep the bottom 

 clean, the supplies of oxygen and food brought by it to the colonies 

 along its path so far exceed I he normal for quiet waters that the ani- 

 mals thus favored flourish and multiply in a manner never seen in quiet 

 deeps. 



The influence of darkness upon the inhabitants of the Abyssal Region 

 has often been expatiated upon. The absence of visual organs, ortheir 

 preternaturally excessive development beyond the normal of the groups 

 to which the individuals belong, is evidence enough that the deeps are 

 markedly darker than the shallows. But this evidence proves too much 

 for the claim that the deeps are mathematically dark. Whatever no- 

 tions may be entertained or conclusions deduced by the physicist from 

 the premises, the presence of large and remarkably developed eyes in 

 many abyssal animals shows that light of some sort exists even on the 

 oceanic floor. It is inconceivable that these organs should be devel- 

 oped without any light, and if the experiments and reasoning of the 

 physicist result in the apparent demonstration of absolute darkness in 

 the depths, the facts of nature show that in his premises or his experi- 

 ments there lurks some vitiating error. It seems absurd to suppose that 

 the phosphorescence of certain animals or parts of animals in the deep- 

 sea fauna is a factor of sufficient importance to bring about the devel- 

 opment of enormous and exquisitely constructed eyes in a multitude of 

 deep-sea species. A greater or general phosphorescence, such as would 

 amount to a general illumination, has never been claimed by any sci- 

 entific liologist, and, as a theory, requires a mass of proof which seems 

 unlikely to be forthcoming. 



In general, then, we find the physical conditions simpler than those 

 of the shallows and yet much more energetic. The effect of tempera- 

 ture is marked in the distribution of life over cold and warmer areas of 

 sea bottom. The relative importance of the effects of pressure, partial 

 darkness, and of the quietness of abyssal waters, our knowledge is yet 

 too imperfect to allow us to precisely estimate. All, doubtless, have 

 their effect; some of the effects are more obvious than others, but it is 

 by no means certain that the most obvious are necessarily the most im- 

 portant to the organisms concerned. 



The mechanical character of the sea bottom is of greater importance 

 than is generally realized. In a very small proportion of its extent the 

 sea bottom is composed of bare, or nearly bare, rock. Away from the 

 shores such a bottom is usually situated in the trough of some great 

 current like the Gulf Stream, and then seems to be nearly bare of ani- 

 mal life. In other cases it may be found on the walls of submarine 

 cliffs, which, for obvious reasons, can hardly be explored for marine life 

 with our present appliances. 



The rest of the bottom consists of solid matter in different stages of 



