Page:A Text-book of Animal Physiology.djvu/36

6 It seems probable that the numerous researches of recent years and others now in progress will open up a new world of cell biology which will greatly advance our knowledge, especially in the direction of increased depth and accuracy.



Though many points are still in dispute, it may be safely said that the nucleus plays, in most cells, a rôle of the highest importance; in fact, it seems as though we might regard the nucleus as the directive brain, so to speak, of the individual cell. It frequently happens that the behavior of the body of the cell is foreshadowed by that of the nucleus. Thus frequently, if not always, division of the body of the nucleus precedes that of the cell itself, and is of a most complicated character (karyokinesis or mitosis). The cell wall is of subordinate importance in the processes of life, though of great value as a mechanical support to the protoplasm of the cell and the