. Elementary text-book of zoology. PROTOZOA. GYMNOMYXA AND CORTICATA. The Protozoa fall into two fairly well-defined Phyla, in accordance with an important character. In the Gym- nomyxa the body of the animal consists of naked protoplasm which has no definite shape of itself. In many cases the protoplasm has a shell to which it clings, inside or outside of it, and under tonic contraction or when the vital processes are dormant it assumes a spherical shape. The nakedness of the protoplasm implies a very low differentia- tion, the alimentary functions of ingestion and egestion being co-extensive
. Elementary text-book of zoology. PROTOZOA. GYMNOMYXA AND CORTICATA. The Protozoa fall into two fairly well-defined Phyla, in accordance with an important character. In the Gym- nomyxa the body of the animal consists of naked protoplasm which has no definite shape of itself. In many cases the protoplasm has a shell to which it clings, inside or outside of it, and under tonic contraction or when the vital processes are dormant it assumes a spherical shape. The nakedness of the protoplasm implies a very low differentia- tion, the alimentary functions of ingestion and egestion being co-extensive with the surface (cf. Amoeba). In the Corti- cata the living organism assumes a definite shape, which is maintained by a hardened cortex and often a cuticle as well. The form of the body is not determined each moment by the forces acting upon it, but a definite shape or plan is assumed and adhered to for each species. A definite mouth, definite egestive spot and definite motor organs are involved. The Corticata are evidently a great step in advance of the Gymnomyxa, from which apparently they have been derived. PHYLUM GYMNOMYXA. Fig. 32.—Types of Foraminiferan Shells (After D'Orbigny). Nodosaria. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Masterman, Arthur Thomas. Edinburgh, E. & S. Livingstone
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