252 THE CONDITIONS OF LIFE IN THE SEA [PART III 



only these influence the metabolism of marine organisms. We 

 know that meteorological changes, so subtle as almost to defy 

 analysis, do affect man and the higher terrestrial animals. Every 

 angler knows that the " rising " of trout is affected by almost 

 imperceptible changes in the condition of the atmosphere. And 

 since the physical organisation of many of the marine animals is 

 hardly, if at all, inferior to that of the terrestrial mammals it may 

 be the case that very slight changes in the physical condition of 

 the sea water affect them also. 



