68 THE HISTORY OF CREATION. 
now add some further general observations on their 
natural history. The great majority of all Protista 
live in the sea,some swimming freely on the surface, 
some creeping at the bottom, and others attached to 
stones, shells, plants, ete. Many species of Protista also live 
in fresh water, but only a very small number on dry land 
(for example, Myxomycetes and some Protoplasta). Most 
of them can be seen only through the microscope, except 
when millions of individuals are found accumulated. Only 
a few of them attain a diameter of some lines, or as much 
as an inch. What they lack in size of body they make up 
for by producing astonishing numbers of individuals, and 
they very considerably influence in this way the economy of 
nature. The imperishable remains of dead Protista, for 
instance, the flinty shells of the Diatomez and Radiolaria 
and the calcareous shells of the Acyttaria, often form large 
rock masses. 
In regard to their vital phenomena, especially those of 
nutrition and propagation, some Protista are more allied to 
plants, others more to animals. Both in their mode of 
taking food and in the chemical changes of their living sub- 
stance, they sometimes more resemble the lower animals, at 
others the lower plants. Free locomotion is possessed by 
many Protista, while others are without it; but this does 
not constitute a characteristic distinction, as we know of 
undoubted animals which entirely lack free locomotion, and 
of genuine plants which possess it. All Protista have 
a, soul—that is to say, are “animate’’—as well as all animals 
and all plants. The soul’s activity in the Protista manifests 
tself in their irritability, that is, in the movements and, 
iother changes which take place in consequence of mechan- 
