Classification

Animal parasites are divided into three classes:-L. Protozoa. 2. Helminths. 3. Arthropedes.

Protozoa include all organisms of the most simple form - the mere beginnings of life, in reality - from the small structureless mass of living-material (bioplasm) to the different forms of cells consisting of a simple investing membrane containing nuclei or sometimes only granular material. Cells assume various forms - circular, oval, elliptical, and elongated.

Protozoa include amoebae, sporozoa, and infusoria. Amoebae have no defined outline, but consist of small masses of living material capable of moving in any direction, and feeding upon particles of food which they find in the fluid in which they live. Those particles they appropriate by enclosing them in the jelly-like material of which they are composed.

Sporozoa are divided into gregarines, coccidia, and psorosperms. They have a more definite form than amoebae, as they are bounded by a cell-wall and contain spores or nuclei. All of these primitive forms of life inhabit stagnant pools, and are consequently taken in by animals which are feeding on the pastures. Their presence has frequently been recognized in the digestive organs of animals, but it is only of late years that the truly parasitic character which some of them assume has been realized. Fatal outbreaks of disease among pheasants and poultry have been traced to the invasion of coccidia, and the presence of the same organism in the ducts of the liver of the rabbit has probably been responsible for a considerable mortality among those animals. The true significance of these lowest forms of parasitic life in the organs of warm-blooded animals is not yet fully appreciated.'