MUSEUM OF COMPARATIVE ZOOLOGY. 21 
closed, then opened when it had reached the requisite depth, and after 
towing horizontally for a time closed by means of a propeller similar 
to the one adopted by Commander C. D. Sigsbee, U. S. N., for closing 
the water cups in use on the “Blake.” Unfortunately, as experience 
has shown, all the experiments made by the “ Vettor Pisani” are vitiated 
by the imperfect method of closure of the rim of the net, and the danger 
that it may open or close again and again on its way up to the surface 
should the hoisting be in the least irregular. 
On the 31st of May, at a depth of 1,800 meters, a small net was at- 
tached below the thermometer, and tripped at the same time as the 
thermometer turned free of the propeller; but on examination of the 
figures of the net in use given on Plate X. by Chierchia, there is no doubt 
that he is correct in stating, “ Anche in questo caso non si può asserire 
che tutta la quantità di animali trovati appartenga agli ultimi strati ove 
pescd il retino.” So that this experiment at least proves nothing, the 
partly open net having passed through the upper 250 or 200 fathoms, 
where there is abundant life. 
On the 5th of June the same experiment was again made on the 
« Vettor Pisani,” at a depth of 1,000 meters; but there is nothing to 
show that, in the surging of the ship and the hauling up, the valves 
of the net have not opened aud closed many times on its way to the 
surface. The same objection may be made to the haul of the 12th of 
June, at a depth of 2,300 meters. 
The experience which all have had who have dredged at sea, of bring- 
ing up fragments of so called deep-sea Siphonophores, was of course also 
that of the “ Vettor Pisani.” Chierchia on the 24th of January, 1884, 
at a depth of 900 meters, let down the wire only, and brought up ten- 
tacles of Siphonophores. To insist, as he and Studer have done, that 
the depth at which these animals lived may be inferred from the length 
of the rope let out by which they reached the surface, is simply to 
ignore the fact that the wire rope on its passage upward through the 
pelagic belt of the fauna may catch anything within those limits. It 
will be seen that Hensen fully concurs with me in considering the 
bathymetrical data obtained by collections from the wire rope or the 
sounding line as of no value. 
The fact that the “Albatross” on her last expedition brought up 
these so called deep-sea Siphonophores, from depths of less than 200 
fathoms, in the open tow-net, which had not been sunk below that 
depth, ought to dispose of the argument of the wire rope catches as 
meaningless. 
