188 “Ch Min CHELD 
their motive power, are comparable rather to the dead than to the 
living organism. They are merely the conditions under which the 
energy acts, but the living organism consists from the beginning 
of these conditions plus the energy. Development is not com- 
parable to the construction of such a machine by man, but rather 
to its action after the steam is turned on. Every steam engine 
possesses a certain power of equilibration dependent upon its 
constitution, and the only reason its powers in this direction are so 
narrowly limited is because the energy current and the structure 
have not been working together from the beginning. 
The only possible basis for a scientific, as opposed to a philo- 
sophical vitalistic hypothesis is the proof that the energy of or- 
ganic life is something essentially different from the energy of the 
physico- chemical world. When the vitalists shall succeed in prov- 
ing this or even in making it probable, then their views will be given 
more general consideration. But even the most extreme among 
this school at the present day do not attempt such proof. If 
we admit that the energy of the organism is not different from that 
in the physico-chemical world, then I believe we are forced to 
regard the organism as a physico-chemical system, for as I have 
shown above, physico-chemical systems exist in which the relation 
between structure and function, between the conditions of action 
and the energy itself, are of the same character as in the organism 
itself and give rise to a power of equilibration of the same character. 
2. Regulation as equilibration 
From what has been said it will be at once apparent that the proc- 
esses which we commonly call regulatory are processes of equili- 
bration in the organism (Holmes, ’04, ’07, Child, ’06, 08a). They 
enable the organism to persist and to maintain its individuality 
under changing conditions, although it cannot be supposed that 
the condition of dynamic equilibrium is the same for different con- 
ditions, and indeed we have evidence that it is not. But within 
certain limits, and for certain factors, the organism is capable of 
a greater or less degree of equilibration, when a change in external 
conditions occurs. 
