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Proceedings of Royal Society of Edinburgh. 
SESS. 
In either case, without doubt the amount found is sufficient to 
account for the growth and accumulation of siliceous organisms in 
modem seas; but a moment’s consideration will show that, by 
adopting the view that siliceous organisms obtain their siliceous 
matter also from insoluble matter floating in the water, we can 
understand to some extent their distribution in the ocean, and how 
they may obtain what to them is a vast local supply (close at hand) 
without being required to deal with an enormous quantity of liquid 
containing but minute traces of silica.* To exemplify what we 
mean, take, for example, an animal requiring, say, 1 lb. of solid 
food per day, this is quickly assimilated with the assistance of 
a small quantity of water ; but if we suppose this same amount of 
solid food dissolved in from 250,000 to 300,000 times its weight of 
water, we are unable to conceive the possibility of the animal assim- 
ilating enough of the solid nutriment contained in this mass of 
liquid to sustain life. 
In a future paper we hope to give further results of experiments 
now in progress on the subjects treated of in this paper. 
In the analyses and determinations referred to in this communica- 
tion we have been assisted throughout by Mr W. S. Anderson, 
Chemist at the Scottish Marine Station, Granton, and we desire 
to thank him for the great attention he has given to all the 
experiments. 
* The abstraction of silicic acid from silicate of alumina will, of course, 
necessitate that an equivalent amount of alumina should be accounted for. 
Doubtless this passes into solution, for in all the sea-waters examined by 
us, after a most careful filtration, alumina has been found in solution (see also 
Dittmar’s Report, Pliys. Chem. Chall. Exp . , part i. ) 
