No. 3-] ATOMS AND MOLECULES. 581 
not be inferred that molecules could not cohere except at such 
nodal points. So long as the atoms vibrate, they produce fields ; 
and this compels the molecules to assume a degree of compact- 
ness that depends upon the strength of the fields, and this may 
take place in the most irregular manner and without any special 
order. A piece of wrought iron may be made crystalline by 
repeated jarring, as it gives to the molecules a transient degree 
of freedom to assume any new position they have any tendency 
to take. In like manner, a bar of iron held in the proper posi- 
tion in a magnetic field will, if jarred by the stroke of a hammer, 
assume polarity; for the jar assists the molecules to rotate to 
the magnetic position induced by the field. But the strength 
of cohesion in crystals is generally less than in amorphous 
bodies, probably from the fact that when the molecules have 
moved to the vibratory nodes, forming geometrical figures, they 
have moved somewhat away from the place of greatest pressure, 
which is where the amount of motion is greatest, the atomic 
impacts at such places tending to move them towards less dis- 
turbed points. When molecules are very compact, such change 
of position is mechanically difficult, and vigorous jarring aids 
somewhat to the rearrangement. Hence the crystallization 
that often takes place in solids like iron. 
Perhaps most who have read this so far have already foreseen 
the bearing it has upon organization as manifested in living 
things, rendering it unnecessary to do more than briefly to 
apply it. 
Chemically, protoplasm is made up of complex molecules, not 
of so great a variety of elements, yet a thousand or more atoms 
in one molecule. As molecules increase in complexity, they 
become less stable, the interior atoms being in a much more 
uniform field than the outer ones, and therefore more easily dis- 
placed; but every such protoplasmic molecule, whether with or 
without a cell structure, must have a mechanical field, and there- 
fore must compel other matter in proximity to it to assume the 
same arrangement as its own. If all the elements necessary 
are available, it will be done; that is to say, the protoplasmic 
mass grows. But this process is called life, or the results of 
life. 
As the mechanical relation to the fed is different for an atom 
deeply imbedded in a molecule from that of one on the surface, 
