THE PHYSIOLOGY OF DEEP-SEA LIFE. 313 
in the food supply of shore animals ; vegetable life forms the 
basis of all life; for while many animals are carnivorous, yet 
those they feed upon depend in a measure for their sustenance 
upon plants. It is therefore an interesting problem to ascer- 
tain how far vegetable life extends into the depths of the sea. 
Its disappearance in comparatively shallow regions is a remark- 
able phenomenon, when we remember that all animal life is 
ultimately dependent upon vegetable life for its own existence. 
The discovery of the carcasses of pelagic animals at the bot- 
tom of the ocean, still fresh enough to supply a large amount 
of food for the animals constituting the deep-sea fauna, solves 
the problem at once. The pelagic animals derive a large part 
of their food supply from the swarms of large and small pelagic 
On dying, 
both surface animals and plants drop to the bottom, and still 
retain an amount of nutritive matter sufficient to serve as food 
for the carnivorous animals living on the bottom. The pelagic 
fauna thus becomes the medium of transfer to the bottom of a 
large quantity of vegetable matter living at the surface. This 
transfer takes place rapidly. Moseley says Salpw will sink two 
thousand fathoms in less than three days. 
The larger carnivorous animals of course prey upon one an- 
other, but foraminifera, sponges, and their allies, cannot feed 
alow covering the surface of the sea in all oceans. 
upon each other, as do the mollusks, annelids, polyps, and the 
like. They need vegetable substances, or diluted organic mat- 
ter, such as they find in abundance on the bottom. 
A sort of “ broth,” as it has been called by Carpenter, collects 
on the bottom of the ocean, from which the lower types may 
possibly be able to obtain their sustenance directly, and transfer 
it for their uses, as they do the silex and lime which they get 
eareous algee are found at that depth, 
would prove conclusively that some kind 
of light penetrates to this depth. Some 
of the organisms which have been de- 
seribed as single-chambered foraminifera 
are in reality calcareous alge, allied to 
the green spore-bearing algæ, the Dasy- 
clade of Harvey. 
Boring algæ have been dredged in deep 
water (over 1,000 fathoms). 
At a depth of 270 fathoms off Havana, 
Pourtalés dredged a single speeimen of 
a minute alga, Centroceras clavulatum 
Aghard, which Harvey says is common 
at low-water mark at Key West. Di- 
atoms were also brought up from the 
same locality. 
