ABSTRACT
The active maintenance of normal and specific structure is what we call life, and the perception of it is the perception of life. The existence of life as such is thus the axiom upon which scientific biology depends.’ This view of the basic nature of biology was the inspiration of the conscious movement for the development of a ‘modern biology’ which took place in Great Britain at the end of the 1920s and early 1930s. The theory of phenotypes is therefore an essential part of the general theory of biology. It will be discussed under a number of separate headings. In biology something of this kind does occur in elementary processes as end-product repression and end-product inhibition, in which the final product of an enzymatic pathway acts so as to control various earlier steps in the sequence by which it is synthesized.
