110 
THE PHYSICAL CONDITIONS OF LIFE IN THE DEPTHS 
OF THE SEA 
By Frank C. Baker, CurATOR OF ZOOLOGY, | Fretp CoLumMBIAN 
EUM OF CHICAGO. 
Recent observations on the deep sea have so enlarged our knowledge 
on that once obscure subject, that we are now enabled to more clearly un- 
destand many of the perplexing phenomena, and to classify the varied and 
curious inhabitants of that region. The results of the Challenger expedition, 
d more recently of the various trips of the United States Fish Commission _ 
steamers Fish Hawk and Albatross, have added rie to, in fact I may 
say have oe us our only knowledge of the deep s 
Formerly, when dredging with the usual ance from small boats, 
150 fathoms 000 feet) was considered the extent to which successful dredg- 
ing could be carried on. Yet within the past ten vears successful dredging 
has been carried on at a depth of about two and a-half miles. If one stands 
on the roof of a high building—say 200 feet high—and looks down, the idea 
of collecting a good representation of the insects and plants on the ground ~ 
at its base by dragging a dredge or trawl by a line let down from the top of 
the building strikes one as preposterous. Yet this is only about arbi 
fathoms high. Multiply this by fifty or sixty and the idea seems e 
unreasonable. Yet living animals have been secured from a aap | of not 
less than one hundred times the height of the house first spoken of. 
The waters of the earth have been divided by naturalists into three 
regions. The first is known as the Litoral Region, which is regarded as ex- 
tending from the actual shore out to the limit of 100 fathoms, and is that to 
whicn light can penetrate, and where, therefore, marine vegetation can ex- 
ist. Beyond this point it is pretty certain that light does not penetrate 
sufficient for the growth of sea-weeds. Outside this 100 fathom limit the 
borders of the continents gradually slope to the bottom of the ocean 
0 
aman Region, the conditions are often very favoraJle for life. There 
are numerous currents of warm, fresh water sweeping along, a8 sup- 
plies food to the animals siong their track. These currents, however, are — 
aba cpg below 700 or 800 fathoms, and this depth ciate to a tem- 
of about 40° Fahr. Beyond the Archibenthal Region the cold, 
... area of the ocean bottom is reached, to which has been applied the 
depth. Below the depth 
found, the temperament diminishes at the rate of one-tenth of a degree to © 
- 100 fathoms, to the freezing point. There is no reason to suppose, however, — 
_ that the water in the Benthal Region ever becomes congealed. Be 
