io6 STUDIES IN INSECT LIFE, ETC. 



whole the abysses of the sea are cold, noiseless, 

 and motionless. The monotony of the surround- 

 ings is increased by the fact that no diurnal or 

 seasonal change reaches those great depths. Sum- 

 mer and winter, spring and autumn, are to them 

 unknown ; for them there is no such thing as 

 night and day, seed-time or harvest. Probably 

 the inhabitants of these abysses breed all the year 

 round, as land-forms do in the tropics. In the 

 tropics with their uniform temperature we find 

 insects and other animals showing no seasonal 

 change of life, eggs, larvae, chrysalises, imagoes 

 all existing at one and the same time. 



Deep-sea animals live at a tremendous pressure. 

 Every five fathoms we descend in the sea the 

 pressure increases by one atmosphere, and at a 

 depth of 3,000 fathoms the pressure on each square 

 inch of the body of an animal amounts to three 

 tons, whereas at the surface of the waters it is 

 about fifteen pounds. So great is this pressure 

 that unless special precautions are taken the glass 

 of the thermometers which measure the bottom 

 temperatures is crushed to powder. 



It used to be thought that the depths of the 

 sea were uninhabitable, and then again it was 

 thought that could we explore them they would 



