biologists who confess
themselves supporters of the mechanical theory, there are some who
expressly reject explanations in terms of chemical and physical
principles, and emphasise, more energetically than others, that these can
only give rise to vital phenomena and complex processes of movement, on
the basis of a most delicately differentiated structure and architecture
of the living substance in its minute details, and from the egg onwards.
They have created the strict "machine theory," and they may be grouped
together as the "tectonists." "A watch that has been stamped to pieces is
no longer a watch." Thus the merely material and chemical is not the
essential part of the living; it is the tectonic, the machinery of
structure that is essential. The fundamental idea in this position is
precisely that of Lotze. It is not a "mystical," vital principle, that
sets up, controls, and regulates the physical and chemical processes
within the developed or developing organism. They receive their direction
and impulse through the fact that they are associated with a given
peculiar mechanical structure. This theory certainly contains all the
monstrosities of preformation in the germ, the mythologies of the
infinitely small, and it suffers shipwreck in ways as diverse as the
number of its sides and parts. But it has the merit of clearly disclosing
the impossibilities of purely chemical explanations. Reinke's "Theory of
Dominants" started from such tectonic conceptions, and so originally did
Driesch's Neovitalism, of which we shall presently have to speak.

Reinke's theory has gone through several stages of development. At first
its general tenor was as follows: Every living thing is typically
different from everything that is not living. What explains this
difference? Certainly not the hypothesis of vital force, which is far from
being clear. The idea that forces of a psychic nature are inherent in the
organism is also rejected. The illustration of a watch helps us to
understand. The impelling force in it is certainly not merely the ordinary
force of gravity or the general elasticity of steel. The efficacy of
simple forces such as these can be increased in infinite diversity by the
"construction of the apparatus" in which they operate. Life is the
function of a quite unique, marvellously complex, inimitable combination
of machines. If these be given, the most complex processes fulfil
themselves of necessity and without the interventi