always a symmetrical, many sided, pliant figure, thrusting out its points of attraction or of repulsion on all sides in symmetrical or balanced actionits multitudes of vibrations balanced among themselves and in adjustment also with all coöperative outside forces.

Do our infinitesimal atoms seem too minute to be the centre of this almost limitless number of structural energies adapted to their corresponding extensions? The infinitely small is not farther from our conception than the infinitely great. If there are 699,000,000,000,000 oscillations in one second in every violet ray of light, if there are 57,000 waves in every inch of the ray, and if each wave travels 192,000 miles every second, there can be no assignable limit to the wonderful forms and energies of the least and weakest atoms. A structure destined to last forever may well be most aptly and marvellously constructed.

PHYSICAL MODIFICATIONS.

The atom a group of interdependent conditions.-Symmetry as necessitated by the atomic conditions.-The pliancy of all structures. Many varieties of crystalline modification.-Pliancy of form in organic and in crystalline structures.-Change in the quantivalence of atoms.-How force and extension condition each other. Two theories.-Motion a necessary relation of conditioned force and extension.-The coöperation of atomic units.

IF

F each unit of being exists as a distinct internally conditioned structure; if it acts from itself in adapted coöperation with multitudes of other units, simultaneously aiding them to carry forward many various processes-every such unit must itself possess a pliant structure whose several parts are so far independent in modes of action that each can perform special functions; though always upon the principle of balanced action among themselves. This unit must be a highly complex unity, whose parts and functions are so mutually adjusted that they are partakers of a common existence. It is a group of interdependent conditions.

A unit thus structurally and functionally con

ditioned would occupy its own position in space; it would have its own rates and amounts of possible internal change and variability of form, to correspond with the variability of functions; and through its coöperation with other units, it could be variously moved and otherwise modified. We have seen that the most elementary substances known to us, when in a gaseous state, are such structurally independent yet externally coöperative systems. We have seen that when two or more of these unite to form a larger system, they modify each other in all their processes; and that they even take a new third position in space. We have seen that through coöperation these various systems are able to move each other from point to point; and to form compounds, with new resultant properties.

Now supposing the atom to be an actual physical structure, it must come legitimately into the rank of physics. We may fairly reason from the established action of the visible body to the necessary action of the invisible one. My theory of the atom is of long standing; it has been carefully considered as to its bearing upon many classes of admitted facts; but

experimental science must establish its crucial tests, if possible, and decide beyond question whether it be true or false.

Here are words written years ago : "I regard the coöperation of forces as comprehending not only the push and counter-push between atom and atom, but also the push and the withdrawal of that push by every atom singly and collectively, when not impeded. in the completion of the process. Every molecule, (and every atom,) it is believed, is itself endowed with the two reactionary types of the one identical force, which together keep it forever pulsing to and fro like the panting heart of a live creature, each atom a microcosm of the universe with its eternal ebb and flow, its systole and diastole." *

But the axis of the atom, its centre of gravity, can never be self-moved. All its vibrations must be balanced within its own structure; and hence, as all its quantities and rates of oscillation are held in check by allied extensions, the form of every atom would naturally be a symmetrical, a well balanced form. The molecule, an association of atoms, would

*Studies in General Science, p. 90.

demand a like symmetry; and molecule joined with molecule in visible masses, being still governed by the same adaptation of energies, should lose nothing in fundamental symmetry of structure. The theory requires visible order, balance, and symmetry in all the forms of Nature.

Facts justify and confirm the theory. Nature has no forms, inorganic or organic, which are so far out of equilibrium in outward shape that they can be thought of in any other way than as produced by some steadily maintained balance of adjusted forces. Very ugly living creatures are on the earth and in the sea; but not one is without real symmetry in the arrangement of part with part; or without an equal adaptation between the creature and its surroundings, however various or peculiar these may be. The temptation to go into detailed illustration is almost irresistible, but the obvious fact is too familiar to require this. There are no one-eyed, one-armed, or one-sided men, except in fable. Single appendages in all animals arise at the junction of the balanced members of the system, or they can be explained as arising from obvious and necessary conditions which