LOTJIS AGA&SIZ 101 



for the fatiguing and sometimes fever 

 ishly hurried tours through the country, 

 which interfered with research and re- 

 acted on his health. Long years of con- 

 stant overwork began to tell on the mag- 

 nificent constitution which had been his 

 best tool ; and during the last twenty 

 years of his life he was interrupted by 

 nervous illnesses, more and more fre- 

 quent, almost always due to overwork 

 of the brain. 



A list of his published writings shows 

 hundreds of technical scientific papers, 

 reprints of popular lectures, reports to 

 the government or to the Coast Survey, 

 addresses on educational subjects and 

 all this besides a miscellaneous scientific 

 correspondence which might have stag- 

 gered a younger man. 



The most ambitious work in original 

 research planned during his American 

 life is the Contributions to the Natural His- 

 tory of the United States. This was to 

 embrace ten large volumes. An elabo- 



