Cytoplasm.

This contains the following essential requirements:

1.       Mitochondria, small rod-like structure which are closely connected with the catabolic, or respiratory, processes of the cell body.

2.       Golgi apparatus. A canal-like structure lying next to the nucleus and involved in the secretory activities of the cell.

3.       Ground cytoplasm. A highly complex colloidal material in which the other structures are embedded. It is largely concerned with the anabolic, or synthetic, activities of the cell.

4.       Centrosome. A minute dense part of cytoplasm, laying close to the nucleus. It plays an important part during cell division.

5.       Cell memberane. The cell boundary is no static envelope. Many important function are connected with it, but in particular its act as a selective sieve through which certain substances are allowed to pass into the cell, or which prevents other substances from gaining access to it. Thus it is most important in maintaining the correct chemical composition of protoplasm.