It is for the sake of a somewhat commensurate appreciation of vitality, of high-wrought molecular organization, that it is necessary, again and again, to point out the might of potentiality intrinsic to matter, the vast and specific stores of force locked up in the peculiar molecular entanglements which constitute our different substances. All forms of matter are essentially magazines of equilibrated energies: inert against such other energies as have no power to disturb their equilibrium, but seething with incalculable commotion against such other energies as have power to disturb their equilibrium.
What H2O is to the steam-engine, the moving substance, the protoplasm, is to the living engine. Machinery is fastened on to both these motor powers exactly in the same manner. The expansion and contraction of H2O give motion to the prearranged and molecularly unyielding levers of the steam-engine. The expansion and contraction of the protoplasm give motion to the prearranged and molecularly unyielding levers of the animal engine. We see the correspondence between an engine and a higher organism is even more complete than is generally conceived by philosophers of the purely mechanical school.
Only, the specific power of the slightly complicated molecule H2O cannot possibly afford any standard for the estimation of the specific power of the immensely more complicated molecule constituting protoplasm. Protoplasm differs from water in proportion to its synthetical wealth. Whatever synthetical wealth may be the symbol of, in its gradations is to be sought the source of all difference in Nature. This is the gist of what chemistry teaches: the work of Nature consists in molecular synthesis. It has required the ceaseless toil of endless ages to build up the molecule of living matter. Let us then value it accordingly, and nevermore view it under the degrading aspect of stolid machinery.
Motility, then, consists in the alternate expansion and contraction of protoplasm, which expansion and contraction are incited by a process of chemical composition and decomposition occurring within the protoplasm. The property of occupying so much more or so much less space, under these different conditions, belongs entirely to the respective organic substances, which alternately fill the larger and the smaller space. The forces which are brought into activity during the process are forces of a known kind, but essentially inherent in the living substance. They are stimulated, not transferred. They are a display of intrinsic power, not an application of extrinsic power. They are not the heat of combustion pushing together or dragging asunder the molecules of the organic substance; they are part of the expression, i. e., of the influence on the medium, of those most specific chemical affinities which synthetical elaboration has ingrained into the constitution of the protoplasm.
If, in contemplating this truth, so positively disclosed by the study of living matter, it should become evident that the display of all other