s called a single sponge is a colony
of animals rather than a single animal; at least they are so regarded by
zooelogists. This can hardly be true if we regard the sponge itself as a
part of the animal. If the sponge is simply regarded as the house in
which the animal lives then it becomes a great tenement with numerous
occupants. But it is a tenement upon which the life of the sponge
depends, and is a part of it.

The sponge could not breathe without the fibrous structure in the cells
containing the machinery for producing the circulation. It will be seen
that the sponge, while it is an animal, is of the very simplest variety,
so far as its organs are concerned. True, its framework is very
complicated, but the organs for sustaining the life of the animal are
the simplest possible. The little self-acting pumps pull the water into
the sponge through the smaller openings, where it appropriates the food
substance from the water and where a chemical action takes place which
builds up the fleshy substance of the animal, and then expels the
residue which is not needed to support its life.

Simple as it is, however, as a mechanical structure, the life and growth
of the sponge is as mysterious as that of the most highly organized
animal or even the soul of man. We can study out the structure of a
plant or animal; we can analyze it and tell what are the elements of
which it is composed; we can describe the mechanical operations that are
carried on and the chemical combinations that take place, but no man has
ever yet solved the mystery of life, even in the lowest form--whether
animal or vegetable.

The sponge, whether considered as a single or compound animal, has the
power to reproduce itself, and here the mystery of life is as much
hidden as it is in God's highest creation. It has been stated that every
sponge contains a large number of separate cells which carry on the
operation of circulation and respiration, and may be likened to the
heart and lungs of an animal of a higher creation. Zooelogists claim that
each one of these cells represents a separate animal, living in a common
structure. However this may be, it is an interesting fact that the
sponge has the power of secreting ova that grow in large numbers in
little sacks until they have reached a certain stage of progress, when
they are expelled from the mother sponge and turned adrift in the great
ocean to struggle for their own existence. These eggs do not differ much