AUGUST. j^^ ^^ ALBATROSS'' EXPEDITION. 449 



even at the greatest depths, and at the greatest distance reached from 

 the shore, distinct traces of terrigenous material were found in the 

 deposits. Sometimes this was a fine sticky mud, at other times there 

 were large quantities of decayed vegetable matter. In fact, during 

 certain parts of the cruise " there was hardly a haul taken which 

 did not supply a large quantity of water-logged wood, and more or 

 less fresh twigs, leaves, seeds, and fruits in all possible stages of 

 decomposition." 



The temperature observations are given in considerable detail, 

 and as the region investigated is traversed by some half-dozen 

 different currents, it would be impossible to give an adequate summary 

 of the results without the aid of maps and diagrams. The most 

 interesting point to notice is that no sufficient evidence was obtained 

 of the updraught of cold water along the western coast of equatorial 

 America, to which Dana and others have attributed the absence of 

 coral reefs in those regions. Agassiz rather believes this to be due 

 to the amount of silt brought down from the land. 



The next section of the Report is the longest, and one of the 

 most interesting. It is devoted to a discussion of the bathymetrical 

 distribution of pelagic life. Professor Agassiz first reviews the older 

 inquiries in this direction, and shows that with scarcely an exception 

 they are all vitiated by defects in the apparatus, and that they are 

 quite inadequate to demonstrate the existence of a populous fauna at 

 intermediate depths, as stated by Professor Haeckel in his " Plankton 

 Studien." In fact, he enters upon quite a sharp passage of arms 

 with the philosopher of Jena, so sharp, indeed, that it must be read to 

 be appreciated. 



Passing by this controversy to consider the facts obtained by the 

 " Albatross," we may remark that the cruise will be memorable for 

 the use which was made of a really practical opening and closing net, 

 "which worked to perfection at 200, 300, 400, and 1,000 fathoms, 

 and had the great advantage of bringing up anything it might find on 

 its way up above the level at which it was towed." This apparatus 

 was due to the ingenuity of Captain Tanner. The net is conical 

 in form, and is suspended from a ring between two ropes, which are 

 weighted at the bottom. About one-fourth up the net two strings 

 encircle it, passing through loops ; to the ends of these strings are 

 attached weights which, when allowed to fall, draw them tight, 

 and constrict off the lower portion of the net. They are, however, 

 held up by a crank, and can be liberated when required by a sliding 

 weight or messenger, which is allowed to run down the line. The 

 difficulty of opening the net under water is obviated by the simple 

 expedient of letting it down with the pointed hinder end first, the 

 pressure of the water being sufficient to keep it pressed tightly 

 together like a folded umbrella. Arrived at the desired depth, the 

 vessel is put in motion, and rope enough is paid out to keep the 

 net moving horizontally, this being judged of by the slant of the rope. 



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