36 BULLETIN OF THE 
views on the population of the intermediate deeper parts of the ocean 
upon the positive results of the “Challenger” tow-nets, we must leave 
him to the full satisfaction of his belief. Haeckel’s ideas of exact exper- 
iments must be very peculiar, if he imagines that an ordinary tow-net 
dropped to any depth, and then towed open all the way to the sur- 
face, will give us any exact data as to what is living at the deepest point 
reached. No amount of differential work will prevent that tow-net from 
gathering the pelagic fauna of the upper belt of 200 to 300 fathoms, 
which all the recent explorations at sea have shown to contain the 
greater mass of the pelagic fauna. 
The dogmatic assertions of Haeckel regarding the value of the results 
obtained by the “ Challenger” tow-nets are in marked contrast with the 
cautious statements of Sir Wyville Thomson, and they may be repro- 
duced here for the benefit of Haeckel. 
In the first place, the tow-net experiments of the “Challenger” were 
only conducted during the last part of the cruise: ‘‘In the investiga- 
tions with the towing-net, made by Mr. Murray during the latter part of 
the cruise—at all depths, the nets being either sent down independently 
to the depths required, or attached to the dredge or trawl rope” ;' and 
while it is true that Thomson thonght “that Radiolarians inhabit the 
water of the ocean throughout its entire depth, or, at all events, its 
upper and lower portions,’? yet we find in his summing up of the 
results obtained from the tow-nets the following statements : — 
“We have every reason to believe, from a series of observations, as 
yet very incomplete, with the tow-net at different depths, that while 
foraminifera are apparently confined to a comparatively superficial belt, 
radiolarians exist at all depths in the water of the ocean. At the sur- 
face and a little beneath it the tow-net yields certain species ; when 
sunk to greater depths additional species are constantly found; and in 
the deposit at the bottom, species occur which have been detected nei- 
ther on the surface nor at 1,000 fathoms, the greatest depth at which 
the tow-net has yet been systematically used ; and specimens taken near 
the bottom of species which occur on or near the surface give us the 
impression of being generally larger and better developed. The results 
from the tow-net are not so directly satisfactory as those from the trawl 
or dredge, which usually bring up animals which we know from their 
nature must have lived on the bottom, and it requires a little consider- 
ation to arrive at their precise value. . . . At present the tow-net, which 
1 Challenger, Atlantic, Vol. II. p. 341. 2 Ibid., p. 340. 
