الفهرس 
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Abstract
The most complex of all physiological processes is growth. In so far as the individual organism is concerned all metabolism is geared towards this end. Although growth is not easy to define it manifests itself in three ways: First, by an increase in size, an effect that is irreversible; Second, by an increase in the number of cells, brought about by cell division accompanied by increase in cytoplasm and other cell components; and third, by a differentiation of the cells so formed into recognizable structural entities.
Increase in size is the visible effect of growth. Naturally, one expects that all processes of growth are accompanied by a net gain in weight. Yet if we should weigh seedlings at different stages of germination, they weigh less than the seeds. But this presents no con- tradiction to the basic fact that growth and development are the result of the complex interplay of many metabolic and biophysical processes in the regions where cells multiply, enlarge and differentiate (Abdel Aal, 1977). While size and fresh weight of a seedling can be measured. at intervals, dry weight can be determined only once for any individual, since it is killed in the process of drying.
In spite of the fact that germination is one of the.