42 THE WORLD BENEATH THE WAVES 



part of the Bay of Bengal, where the mean surface 

 temperature is about 80° Fahrenheit, the temperature 

 at a depth of 100 fathoms is only about 60°, at a 

 depth of 300 fathoms not quite 50° ; while at a depth 

 of 2000 fathoms the temperature all the year round 

 is only 3° above freezing point. Though this low 

 temperature is an effect, it would be incorrect to 

 call it the direct effect, of the obscuration of the 

 sun : as a matter of fact, the bottom temperature of 

 the Bay of Bengal is believed to be directly determined 

 by under-currents, that is to say bottom-currents, of 

 cold water constantly creeping onwards from the South 

 Pole. But, as the shepherd's philosophy informed 

 Touchstone, '*a great cause of the night is lack of 

 the sun " ; so the cold of the bottom of the ocean 

 may be rightly attributed in the last resort to the 

 same great cause. 



We see, then, to conclude the matter, that life in 

 the rather monotonous depths of the ocean is con- 

 ditioned in ways a good deal different from the life 

 of the land and of the littoral. 



In the first place, plant life is impossible, because 

 there is no sunlight, although bacteria and other 

 miicroscopic parasitical plants that do not require sun- 

 light may and do exist there. But the bulk of life 

 is animal life accustomed to an enormous hydrostatic 

 pressure, to a low temperature, and to gloom or dark- 



