Growth is a fundamental property of living
matter. It depends upon the reception of an appropriate stimulus by a potentially reactive cell, under
conditions which permit this to respond.
In the higher forms of life the elaboration of
specific growth stimulating substances is a function
of the endocrine system, increase in size and complexity of the organism as a whole being regulated
by the glands of internal secretion, such as the
thyroid, and the anterior lobe of the pituitary body.
But no less essential to the process of growth are
those chemical substances which are derived from
other sources and are concerned in the general nutrition
of the organism, as, for example, certain of the
amino -acid constituents of proteins.
Such nutritive substances are complementary to
the specific harmonic growth activators, for they
provide that particular chemical environment in whit
a specific stimulus can evoke from the living tissue
a maximum and sustained response.
This study is concerned with the nature and
action of certain non -specific growth promoting
agencies, which are constituents of the protein