Abstract
Growth is defined as the normal changes in the amount of living substance.
Development refers to all the naturally occurring unidirectional changes in an
individual's life, from its existence as a single cell to its elaboration as a multifunctional
unit terminating in death. It encompasses the normal sequential events between
fertilization and death. Note that development to the biologist refers to the individual in
contradistinction to species. The life of the individual does not start as a gamete or
zygote, but as primordial germ cells that give rise to gametes. In some invertebrates
and plants, life starts from almost any cell which is properly stimulated and maintained.
The term multifunctional unit emphasizes the elaboration of multiple functions rather
than multiple cellularities. Unidirectional changes continue until death. Therefore,
development is a result of a combination of growth, differentiation, and translocation:
These terms are not synonymous.