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that work upon the fishes of Brazil, his first Work, which he 

 had published when he was twenty-two years old. 



He spent the leisure of several years in examining the reefs 

 and dredging in the waters of the coast of Florida and other 

 parts, always bringing home stores of new species and genera, 

 and completing the history of innumerable known ones. 

 What a preparation were these years for the great Hasler ex- 

 pedition, in which the depths of the ocean were very fully 

 explored, and innumerable objects, new and old, were brought 

 up, showing that the bottom of the ocean is any thing but 

 barren, and throwing new light upon the geology of recent 

 and of ancient times. 



Whenever Mr. Agassiz undertook a special work, he pre- 

 pared himself for it by a careful study of whatever had been 

 done in that particular line by all others. He had seen, every- 

 where, indications of the action of ice. He determined to 

 investigate. He began by reading all he could find upon the 

 subject, and then set himself to observe, patiently and care- 

 fully, what was taking place in the glaciers themselves. He 

 gave the leisure of several years to this examination, and 

 then felt himself ready to observe the effects of similar ac- 

 tion in former ages and distant regions. The opinions of 

 such an observer, after such a preparation, cannot be without 

 authority and value ; and it. is not surprising that he should 

 not himself have been willing to yield them to those oi 

 others who had never given the same study to the subject. 



When he wrote his wonderfully compltte work upon the 

 American Testtidinata, he began by studying whatever had 

 been written in regard to that family of animals, and he fur- 

 nished himself; by the liberal aid of many friends, with im- 

 mense numbers of specimens, so that he had ample means of 



