1892.] The Problem of Marine. Biology. 801 
The existence of this intermediate pelagic fauna was called 
in question by Alexander Agassiz, on the ground of the lia- 
bility of error in using the ordinary open net instead of one 
which could be closed at a definite depth and then drawn up ; 
and more particularly upon the ground of his own experi- 
ments made in 1878 on the “ Blake” expedition. He believes 
that the great bulk of the ocean contains no organic life at all, 
that the surface fauna of the sea is limited to a relatively thin 
layer, and that there is no intermediate layer, so to speak, of 
animal life between the fauna of the bottom of the deep sea 
and of the surface. 
Agassiz’s results are contradicted by those of Chierchia on 
the Italian corvette “ Vettor Pisani.” With the closable net 
invented by Palumko he brought up an astonishing quantity 
and variety of forms of life from different depths, even up to 
4000 meters. Prof. Carl Chun, with an improved closable net, 
studied the marine fauna and flora of the Gulf of Naples. 
He formulates his results as follows: 1. That part of the Med- 
iterranean investigated showsa rich pelagic life even to a depth 
of 1400 meters, as well as at the surface. 2. Pelagic animals, 
which during the winter and spring appear at the surface, at 
the beginning of summer seek the depths. 3. At greater 
depths pelagic animals occur, which hitherto have seldom or 
not at all been observed at the surface. 4. A number of 
pelagic animals during the summer remain at the surface and 
never go into the depths. From his observations upon the 
vertical distribution of marine life he was led to remark that 
the surface fauna was apparently only the advance guard of 
the vast army below. His conclusions were confirmed by 
observations made during a trip to the Canary Islands, and 
agree with those made by Prof. Haeckel twenty years before. 
Prof. Hensen, of Kiel, has for several years past been study- 
ing the phenomena of pelagic life with a view of ascertaining 
its relations to the fisheries question. He has proposed the 
term Plankton (from dopa, to wander) to designate this 
world of marine life. Prof. Haeckel agrees with this and 
adds Planktology, that branch of biology which deals with 
the study of the Plankton. Prof.-Hensen hopes to gain val- 
