COLLECTING AND TRAPPING 105 



part in procuring them. Although the ordinary trawling- 

 dredge brings up a vast amount of material useful to the 

 biologist — including shrimps, which, boiled in sea -water and 

 eaten hot, whilst the boat runs lazily before the wind dragging 

 the trawl, are things to be remembered, — special trawls have 

 been invented for special purposes, and the following describes 

 one particularly interesting : ^ — 



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 1000 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 liber- 

 ated 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. After towing for, say, twenty minutes, the net is again brought 

 to the vertical, and the messenger sent down to close it ; after which it 

 is brought up to the surface, and the contents of the upper and lower 

 portions of the net examined separately. 



This net was used on several occasions in water of considerable 

 depth, and undoubtedly failed to produce evidence of a mid-water fauna 

 of any variety or abundance. The number of unexceptionable trials at 

 depths of 400 fathoms and upwards was, however, too small to justify 

 any far-reaching conclusions. 



1 " The Albatross Expedition," Natural Science, August 1892, pp. 449, 450. 



