REGULATORY PROCESSES IN ORGANISMS 221 
processes following experimental section and the physiological 
solation of parts is of the greatest significance for our conception 
and solution of the problems of inheritance and development. 
CONCLUSION 
It is sufficiently evident from what has been said that I consider 
the phenomena of regulation in organisms as constituting the es- 
sential chacteristic of life as a continuing process. I agree with 
Jennings that the problem of regulation is the fundamental prob- 
lem of life. All of our experimental investigations on living organ- 
isms are directly concerned with the problem of regulation in 
one way or another. In fact there are only two possible methods 
of investigating and analyzing the phenomena of life: one is con- 
cerned with regulation in the living organism, the other with the 
observation and analysis of the results of stopping the life-proc- 
esses at this or that particular point, under these or those parti- 
cular conditions. In the one case we observe and control the proc- 
ess in its action, in the other we seek to determine the effects of 
its past action. As we can watch the river at work and investi- 
gate the processes of equilibration resulting from alteration of its 
flow in one way or another, so we can investigate the living organ- 
ism. And as we can stop the flow of the stream or divert it into 
other channels and determine something of what it has done along 
its course up to a certain time by examination of its channel, so 
from the dead organism, we can determine something of its past 
activity. 
But the conclusions drawn from the examination of the channel 
of the ‘dead’ river are only fragmentary at best. Only by observ- 
ing and controlling the river in action is it possible to acquire any 
adequate conception of what it really is. And so, I believe, with 
regard to the organism: the living organism will teach us more than 
the dead, one though we must work with both. And when 
we work with the living organism we come at once face to face 
with the problem of equilibration, of regulation. And finally, I 
believe that the further our knowledge of the processes of equili- 
bration. in the organism advances, the greater will be the difficulty 
of finding an adequate foundation in biology for vitalistic or 
dualistic hypotheses. 
