OCEAN TEMPERATURES AND CURRENTS. 243 



in the body, and it is certain that we owe a great deal 

 to them in the daily economy of nature. 



Upon the organization of the United States Fish 

 Commission, the essential problems to be studied were 

 properly believed to be largely biological in character. 

 Some attention was paid to the physical conditions 

 under which marine life existed, but the bearing of 

 these conditions upon the successful propagation of fish, 

 or the uses which could be made of a careful study of 

 these conditions under given states of the air or sea, 

 was not deemed an important item in the problem 

 placed before the Commission for their consideration. 

 The result was that the early work of the Commission 

 was devoted to the collection of specimens of fish and 

 other forms of marine life, the study of their distribu- 

 tion, and the discussion of their embryological develop- 

 ment. After this, the examination of the food of 

 these fishes and their physical surroundings attracted 

 attention. 



When the attempt was made, however, to compare 

 the isolated observations upon the temperature and 

 specific gravity of the waters, it was found that suf- 

 ficient data of a proper character were not at hand to 

 give a complete and satisfactory basis for an explanation 

 of the phenomena which were known to exist. The 

 necessity then presented itself of making a more system- 

 atic survey of some specific coast region, with the view 

 of obtaining the law of the changes which take place 

 under given conditions. 



If the changes which take place in the temperature 

 and specific gravity of the waters influence the move- 

 ments of the schools of fish, then the various move- 



