ORIGINATION OF SELF-GENERATING MATTER 607 
plasm. Few adjustments are so simple, and, of course, more com- 
plicated ones became possible as atomic group after atomic group 
was added to the constituency of living matter. 
Along with these acquisitions the feature of the rhythmic action 
which has become so characteristic and important for the living 
growth is to be considered, and this with contractility is dependent 
upon surface tension, viscosity, etc. 
So far the properties suggested are those common to all living 
forms, but there must have ensued many differentiations of living 
matter, of which we have two survivals in plants and in animals. It 
seems probable that the first specialization resulted from the forma- 
tion of substances in some of the living masses which converted radia- 
tions of certain wave-lengths into heat and other forms of energy 
active in promoting the reduction processes. A fortuitous move- 
ment toward such specialization may indeed have been the factor 
that made for survival in an environment of decreasingly avail- 
able supply of chemical energy. The highest development of this 
power of absorption of light rays is to be assigned to chlorophyll, 
but preceding the formation of this very intricate and unstable sub- 
stance there may have occurred a series of other compounds acting 
as heat-absorbent screens, of which the reddish and bluish pigments 
of the lower algae are surviving examples. Many disintegration 
products constituting the reds and blues of plant tissues sustain 
physical relations of a similar character to sunlight. 
It is not possible to formulate any rational conception of living mat- 
ter without including its environmental relations. These become of 
the utmost importance at the moment of formation of self-generating 
matter, and it may be assumed with perfect safety that of all the pos- 
sible synthetic processes only those which ensued in the presence of a 
medium which furnished substances suitable for building material 
could survive. Furthermore, when the accumulation of this material 
and its specialization is considered it is apparent that successful 
origination occurred only on solid or semi-solid substrata rather than 
in undifferentiated solutions in open waters. Still an abundance of 
this liquid would be of great importance to the colloidal masses which 
we may think of as the earliest living things, and, as will be shown 
presently, water has continued to be the most important of all of 
