1891.] 
199 
[Dolbear. 
a view of vital actions as they hold is incomparable with almost 
everything we know about the relations of energy to matter. The 
works of the later physiologists abound with statements that in- 
dicate all the phenomena they have to consider are physico chem- 
ical and nothing different. Thus, Foster, one of the most eminent, 
says, “The physiologists have been led to consider the qualities of 
things as being expressions of internal movements ; even more 
imperative does it seem to us that the biologist should regard the 
qualities of protoplasm as in like manner the expression of internal 
movements. He may speak of protoplasm as a complex sub- 
stance, but he must strive to realize that what he means by a 
complex substance is a complex whirl, an intricate dance.” And 
again, “The more these molecular problems of physiology are 
studied, the stronger becomes the conviction that the considera- 
tion of what we call structure must, in harmony with modern 
teachings of physics, be approached under the dominant concep- 
tions of modes of motion.” “The phenomena in question are the 
result not of properties of kinds of matter but of kinds of motion. ” 
Well, then, if biological phenomena are not different in kind 
from those generally known as chemical it follows that the factors 
and operations that explain the one will explain the other also. 
Chemically protoplasm is made up of complex molecules, not 
of so great a variety of elements, as a relatively larger number of 
them, a thousand or more perhaps in a molecule. Generally as 
molecules increase in complexity they become less stable. If a 
molecule be so large as to have some of its constituent atoms 
wholly inclosed within its surface, and if each atom maintains in 
a measure its characteristic motions the interior atoms must be 
in a much more uniform field than the external ones, and there- 
fore so much more easily displaced. There must be a greater 
tension upon the external layer of atoms than upon the rest. 
This phenomenon is well known even upon large masses of liquids 
and is called surface tension. The explanation here given is that 
this is the necessary result of the mechanical field of pressure and 
hence then a greater degree of stability would be fc looked for in the 
material of the outside than upon the inside and so cellular struct- 
ure is the mechanical expression of the relation of the molecules 
and their field. 
The field of a given cell must depend upon the elements that 
compose it, their number and arrangement, and for any one of 
