1894,] The Energy of Evolution. 209 
elaboration of these substances is not accomplished by anage- 
netic or “ vital” energy, but by a process of running down of 
the higher compound protoplasm, which is catagenesis. No 
truly anagenetic process has yet been imitated by man. 
All forms of functioning of organs, except assimilation, repro- 
duction and growth, are catagenetic. That is, functioning 
consists inm the retrograde metamorphosis of a nitrogenous 
organic substance or proteid with the setting free of energy. 
The proteid is decomposed in the functioning tissue into 
carbon dioxyd, water, urea, etc., and energy appears in the 
muscle as contraction, in the glands as secretion, and in all 
parts of the body as heat. The general result of physiologic 
research is, that the decomposition of the blood is the source of 
energy, while the tissue of each organ determines the character 
of that energy. That the tissue itself suffers from wear, and 
requires repair, is also true, but to a less extent than 
was once supposed. 
In the anagenetic process of the growth of the embryo the 
case is different. Here the processes of functioning of organs 
are in complete abeyance, the nutritive substance is not 
entirely broken down in chemical decomposition, but it is in 
great part elaborated into tissues and organs. All the 
mechanisms necessary to the mature life of the individual are 
constructed by the activity of the special form of energy known 
as growth-energy or Bathmism. It is the modifications of this 
energy which constitute evolution, and it is these to which we 
will hereafter direct our attention. Its simplest exhibition is 
the subdivision of a unicellular protoplasmic body into two or 
more individuals or structural units of a multicellular organism. 
Further division of the latter does not abolish theindividual, but 
extends it, and we now observe the elaboration of different 
structural types to become a conspicuous function of this form 
of energy. In other words a once simple energy becomes 
specialized into specific energies, each of which, once estab- 
lished, pursues its mode of motion in opposition to all other 
modes not more potent than itself. Besides the evident truth ` 
of the proposition than a mode of building is a mode of motion, 
we have another very good reason for believing in the existence 
