i; LOUIS AGASSIZ. [CHAP. \x. 



zons was good, but it is no wonder that at last he was 

 overcome by fatigue, and though not actually ill, 

 was exhausted by incessant work, and by the contem- 

 plation, each day more vivid and impressive, of the 

 grandeur and beauty of tropical nature. On his re- 

 turn to Para, where he arrived in February, 1866, he 

 was so tired as to be unable for several days to exert 

 himself even to write letters. The climate had affected 

 and enervated him more than he had at first thought. 

 If Agassiz had made an exploration of the Amazons 

 thirty years before, when still in the prime of life, the 

 results would have been very different. Although he 

 had undoubtedly acquired great practical experience on 

 all zoological questions, and made good use of that 

 experience during his journey up and down the great 

 Amazons, he was too old to make a full use of his rare 

 ability as an observer. His mind was no longer so 

 elastic as at the time of his sojourn on the glacier of 

 the Aar, and although his eagerness to collect speci- 

 mens was as great as ever, he had no longer the bodily 

 strength to make full use of them. 



vCertainly his " Brazilian expedition, fitted out and 

 sustained by individual generosity, was treated as a 

 national undertaking, and welcomed by a national hos- 

 pitality," and Agassiz succeeded in bringing safely 

 home to his museum the treasures he accumulated in 

 Brazil ; but it remained to work them up, to classify 

 them systematically, and, as he himself says, " a critical 

 examination of more than eighty thousand specimens 

 cannot be made in less than several years." Unhap- 

 pily this critical examination, for some reason or other, 



