PRESIDENTIAL ADDRESS. J> 



fauna is a factor of sufficient importance to bring about the 

 development of enormous and exquisitely constructed eyes in a 

 multitude of deep sea species. A greater or general phospho- 

 rescence, such as would amount to a general illumination, has 

 never been claimed by any scientific biologist 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 temperature 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 impor- 

 tant to the organisms concerned. 



The mechanical character of the sea bottom is of greater im- 

 portance than is generally realized. In a very small propor- 

 tion 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 animal life. In 

 other cases it may be found on the walls of sub-marine 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 sub-division, from something which may be described 

 as calcareous gravel to an impalpable mud which may or may 

 not be dotted with concretions of manganese, iron or other 

 mineral matter. The gravels are chiefly confined to the archi- 

 benthal region, the true deeps are generally carpeted with a 



