200 THREE CRUISES OF THE " BLAKE." 



I made no attempts to use the tow-Det to ascertain the pre- 

 sence of foraminifera, radiolaria, or other pelagic animals, at a 

 distance from the surface. All naturalists famiUar with the use 

 of the dip-net, the tow-net, or with their modifications first em- 

 ployed below the surface by Baur, know that the pelagic ani- 

 mals are driven from the immediate surface by winds and rain, 

 or by some other cause, into moderate depths, where they may 

 always be procured, while at greater depths they fail to be found. 

 Such, at least, has been the experience of Johannes Miiller, 

 Claparede, and others, who have followed their method of fish- 

 inof either at the surface or a little below it. 



The evidence of specimens brought up by the '' Challenger " 

 nets from intermediate depths is inconclusive, since the ordi- 

 nary tow-nets were used. These were lowered open, kept open 

 while towing, and remained open while coming uj). It is per- 

 fectly true, that, by differentiation of the contents of the several 

 nets at one locality, some approximate results might be obtained, 

 if the Avork were carried on for a long period ; but an occasional 

 haul taken by itself means nothing. The important desideratum 

 is to devise a tow-net which will go down closed to any depth re- 

 quired, will then open and tow while the ship is in motion, and 

 close again within a reasonable distance as it comes up. The 

 collecting cylinder devised by Lieutenant-Commander Sigsbee 

 meets some of these requirements.^ He accompanied us on the 

 " Blake," to superintend in person its first trial. It was sent 

 down in thirty fathoms of water, from live to twenty-five fath- 

 oms, with quite a fresh breeze blowing, at about eleven in the 

 morning, in full sunlight, — a time when, with a smooth sea, 

 the pelagic animals would all have been on the surface. The 

 cylinder worked most satisfactorily, and brought up a few Calani, 

 hydroid medusae, such as usually occur at the surface. A few 

 slioht chano-es were suofo-ested bv the desionei-, and Commander 

 Bartlett recommended the addition of a wire-gauze trap, to 

 facilitate the washing out of microscopic animals. 



On the 1st of July the Sigsbee cylinder was tried for the 

 second time, in Lat. 39^ 59' 16" N., Lon. 70° 18' 30" W., in 

 two hundred and sixty fathoms of water. The surface was 



1 Described in the chapter on the Equipment of the " Blake." 



