protozoa

The lowest Protozoa are entirely without any system of colouring; being merely of uniform tint, generally of brown colour.

By far the most important addition is the inclusion of an entirely new section on Pathogenic Protozoa.

Such lowly organized forms are known to naturalists as the Protozoa.

The present chapter will be devoted to the Protozoa—the sub-kingdom that includes the simplest of all animal beings.

These cells, called choanocytes, resemble independent animals of the Protozoa, known as flagellate Infusoria or Choanoflagellata.