The New Student's Reference Work/Cell

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Cell (in plants), the unit of structure in the bodies of plants and animals. The bodies of the smallest plants consist of a single cell, while those of the more complex plants consist of very many cells. The free cell is approximately globular in outline, but if pressed upon by neighboring cells it may become variously modified in form.

NSRW Plant Cells by Age.jpg
PLANT CELLS OF DIFFERENT AGES

Bounding the ordinary plant-cell, there is a thin elastic wall composed of a substance called cellulose. This cell-wall forms a delicate sac within which there exists the living substance called protoplasm. It is this substance which is alive and works, and has really formed the cell-wall about itself. The protoplasm of a living cell is organized into various NSRW Ulothrix.jpg
ULOTHRIX, SHOWING THE FORMATION, ESCAPE AND BEHAVIOR OF SWIMMING CELLS
structures, which have different duties. One of the most conspicuous structures is a more compact mass of protoplasm, usually of spherical form, which is called the nucleus. The nucleus is imbedded in the less dense protoplasm, which receives the general name cytoplasm. In addition to its power of growth the living cell is also able to divide itself into two cells. The process of ordinary cell-division is an exceedingly complicated one, and is known as mitosis or karyokinesis. It is this power of self-division which enables a single cell, such as an egg, to produce eventually a complex body composed of numerous cells.

John M. Coulter.