82 
the specific gravity of the water is comparatively low. Again 
(Voyage of the Challenger, vol. ii., p. 339), ee the frustules of 
Diatoms occur in all the deep-sea deposits in greater or less 
number ; and in some places, as at a few of the stations in 
the Indian Ocean, they form the bulk of the sample brought 
up by the sounding machine.” 
The stomach of Holothuridea taken over this area was 
found to be “ distended with the ( diatom-ooze 3 so completely 
that the animal looked like a thin transparent bag filled with 
it.” 
Again, it is well known that diatoms are found in the 
stomach of fish and crustaceans, and, moreover, of purely 
pelagic forms, as of Salpce. Much still remains to be done 
in the study of marine life, but we may confidently expect 
that it will exhibit subordination to the same great laws of 
nutrition as those exemplified in terrestrial life. 
Since writing the above, I have read in a daily paper a 
remarkable confirmation of the assertion made of the import- 
ance of Diatoms. The contributor was describing the 
cod-fishery. The existence of the Newfoundland shoals, he 
says, depends upon a great Polar current which flows that 
way from the Arctic regions. This current gives the fish the 
cold water they like, and also brings them the food they 
require. From the way in which he describes the food as 
colouring the sea green or brown, it is pretty clear that he is 
speaking of minute Algce, probably Diatoms. 
We can scarcely allude to carnivorous animals without 
being reminded of the sensational descriptions of the so- 
called cruelty of nature given under this head by Pessimists 
and Sceptics. May we ask, in reply, what other arrangement 
they can propose ? If all animals fed on vegetables, they 
would sooner or later exhaust the supply and perish by 
famine. The Utilitarians set up the principle of the Happi- 
ness of the Greater Number as their guide. Is not this 
precisely what now results from the system of checks and 
counter-checks which keeps up the due balance of Animated 
Nature ? 
Closely connected with the primary function of the Vege- 
table Kingdom are subsidiary purposes fulfilled by it. In the 
first place, it purifies air and water. The gas carbon dioxide 
is produced in large quantities by the respiration of animals, 
on land and in the sea, and also by artificial combustion. This 
noxious compound, if not got rid of, would accumulate through 
its weight in the lower strata of the atmosphere, so as to be 
fatal to all life on the globe. But plants consume it, as I have 
