THE FIRST ALBATROSS EXPEDITION 265 



servers had led to a different conclusion, he was inclined 

 to attribute it to the defective working of the apparatus 

 used. His experience in the Gulf of California, on the 

 other hand, led him to believe that in a comparatively 

 closed sea there may be a mixture of the pelagic species 

 with the free swimming animals that live at or near the 

 bottom. 



This was with one exception the last of Agassiz's ex- 

 peditions that was purely zoological. The main object 

 of his subsequent voyages was the investigation of coral 

 reefs and coral islands, and the questions arising from 

 the study of their formation. During the latter part of 

 his life he does not appear to have been greatly inter- 

 ested in the question of the vertical distribution of life 

 in the ocean. On only two of his later trips did he ever 

 use a Tanner net. On the Wild Duck in 1893, he made 

 some casts with one off Havana, and a few in the Tongue 

 of the Ocean in the Bahamas, which led him in no way 

 to modify his views. 



Some months after this last expedition, he says, in 

 writing to Dr. Giesbrecht : — 



" I do not wish in any way to be obstinate about my 

 views as to the extension of pelagic life — not necessarily 

 surface forms — to great depths. All I care to know 

 positively is, whether at sea, far from land, the sheet of 

 water below 250 or 300 fathoms is populated densely 

 or so sparsely as to enable us to say that animal life 

 practically ceases at the depths of 250 to 300 fathoms. 

 I am not fighting for any theory, I am only stating my 

 experience, and it is very strange that I have so inva- 

 riably been unsuccessful in tracing the existence of 

 animal life below the above-mentioned limits, while 



