VII.—THE SINGLE-CELLED ANIMAL BODY; PROTOPLASM AND THE CELL.
The single-celled animal body, [36.]—The cell, [37.]—Protoplasm, [39.]
VIII.-CELLULAR STRUCTURE OF THE TOAD (OR FROG).
[Laboratory exercise], [40.]—The blood, [40.]—The skin, [40.]—The liver, [41.]—The muscles, [41.]
IX.—THE MANY-CELLED ANIMAL BODY; DIFFERENTIATION OF THE CELL.
The many-celled animal body, [43.]—Differentiation of the cell, [43.]
X.—HYDRA.
[Laboratory exercise], [46.]
XI.—THE SIMPLEST MANY-CELLED ANIMALS.
Cell-differentiation and body-organization in Hydra, [52.]—Degrees in cell-differentiation and body-organization, [54.]