The study of the normal function of the animal and human organisms and
of the diseases which disturb that normal func- tion is largely the
study of control mechanisms. These control mechanisms are essential for
the survival of an organism in a more or less hostile environment. In
many ways they clearly resemble the control mechanisms devised by
electronic engin- eers for running machinery of all kinds and there are
many remarkable parallels between biology and engineering. However, it
should not be forgotten that the biological systems were on the scene
first and that the engineering is a parallel and independent
development. It is therefore perhaps a pity that in recent years the
study of biological control systems has tended to be dominated by
mathematicians and engineers who have moved from these more precise
disciplines into biology. As a consequence of this dominance, one often
gets the impression that the principles of biological control can be
understood only after one has undergone a rather high-powered course in
elec- tronic control theory. It often seems to be assumed that it is
electronics which must do all the teaching while biology and medicine
must do all the learning. In fact I suspect that biolo- gical control
mechanisms are considerably more sophisticated than anything yet
available in the world of the physical sciences and that in the long run
biology will teach more to control engineers than vice versa.