The Protozoa, or one-celled animals (nearly all microscopic).
The mode of feeding of the sponge is very similar to that of the protozoa.
Two things must be noticed before we leave the subject of the Protozoa.
The animals which are higher in structure than the Protozoa, viz.
The first grade includes only the Protozoa, or unicellular animals.
These protozoa possess, as ...