88 THE FITNESS OF THE ENVIRONMENT 



be cited as a good illustration of the nature of 

 the case. 1 



It is unnecessary to discuss the effects 

 upon living organisms of the equable tem- 

 perature of the ocean and of the moderation 

 of climate, for obviously we are here confronted 

 by a true instance of regulation of the environ- 

 ment. 



The high heat capacity of water operates 

 in still another manner to regulate tempera- 

 ture upon the land and at the same time to 

 increase the mobility of the environment of 

 marine organisms. For directly or indirectly 

 it is involved in the formation and duration 

 of ocean currents, especially the movement of 

 water in the depths from the polar to the 

 tropical seas, and it determines the amount 

 of heat carried by such currents. A similar 

 and even more important "function" is the 

 direct promotion of winds, with the resulting 

 distribution of aqueous vapor throughout the 

 atmosphere, a primary factor in the dissemina- 

 tion of water by means of the rainfall. Here 

 the essential thing is the existence of a vast 

 warm reservoir in the tropics and of two 

 similar cold reservoirs at the poles. Under 



1 A discussion of Zenker's work will be found in Hann's 

 "Handbook of Climatology," translated by Ward, pp. 210- 

 215. 



