ORGANIC REGULATION 101 
us are capable of unification under our guiding 
hypothesis ; and we proceed to investigate them further 
with this faith present to us. We notice, for instance, 
that animals breathe. The breathing is a manifesta- 
tion of the animal’s life, for any hindrance to breath- 
ing is violently resisted with the animal’s whole 
available power. Further investigation shows us more 
definitely what breathing is, the essential element in 
breathing being the due supply of oxygen to the body, 
and removal of carbon dioxide. By more detailed 
investigations, such as I have endeavoured to describe 
in these lectures, we reach a further knowledge of how 
the phenomena of breathing are integral manifesta- 
tions of the whole life of the organism, including its 
past history ; and the aim remains before us of reach- 
ing similar knowledge of how the development, main- 
tenance and functional efficiency of each structural 
element are regulated. 
One of the earliest steps in this voyage of discovery 
is to find any detail of structure or activity that can 
be regarded as a “normal.” We look for normal 
structure, normal chemical composition, and normal 
standards of activity. And we do so because we know 
that life maintains itself: that this maintenance ex- 
presses itself in normals for everything connected with 
life. In the inorganic world there appear to be no 
normals in this sense; and chance, not order, seems, 
to the present very limited vision of physical science, 
to reign supreme. 
When we have found what appears to be a normal, 
such, for instance, as a normal concentration of carbon 
