And these unicellular animals have the rudiments of all our functions.

We have first to distinguish the unicellular animals (protozoa) from the multicellular tissue-forming (metazoa).

We must emphasize that these little animals correspond in all essential respects to the cells of our bodies; they are unicellular animals.

Man's ancestry, it seems, from the scientific evidence which has been marshaled, may be traced back biologically, in an almost unbroken chain to unicellular animals.