1] MICROSCOPIC PLANTS. II 
examined were invariably charged with diatomaceous 
remains, constituting a bank which stretches 200 
miles north from the base of the Victoria Barrier, 
while the average depth of water above it is 300 
fathoms, or 1800 feet. Vast quantities, again, occur 
in beds under the guise of a white powder, which is 
called mountain meal, and is actually mixed with 
flour in some parts of Sweden, though it is perfectly 
inert, and can serve merely to increase the bulk of 
the food.” 
Mr. W. H. Shrubsole, F.G.S., has recently discovered 
the presence of these ubiquitous organisms in the 
London Clay formation, About . 
twenty species have already been 5 ih 
identified, but there are also a & Ge) om 
number of species new to micro- sis 
scopists. Mr. Shrubsole reports that he has traced 
the diatomaceous zone for several miles, and is still 
pursuing the inquiry. 
Some of the water-snails and other molluscs sub- 
sist largely upon these Diatoms, and many rare 
species have been obtained from the stomachs of 
fish, They can endure the greatest degree of cold 
without injury to their vital powers, and some have 
been found in hot springs. 
All these plants we have mentioned belong to the 
sroup of Alg@, they all possess chlorophyll, and are 
able to live upon the most simple chemical com- 
pounds. We have next to glance at a group of 
plants which never possess this chlorophyll, and can 
only live on organised matter. To commence with, 
we could not have a better subject than the Yeast- 
