that every distinct chemical substance of the living body will ultimately be produced in the laboratory; and this from inorganic materials. Given only the exact constitution of a compound, and its synthesis follows. When, therefore, the chemist shall succeed in producing a mass constitutionally identical with protoplasmic albumen, there is every reason to expect that it will exhibit all the phenomena which characterize its life; and this equally whether protoplasm be a single substance or a mixture of several closely allied substances.
But here a word should be said concerning a remarkable physical condition assumed by matter in organized beings. Graham, in 1862, drew the sharp line which separates colloid from crystalloid matter. "His researches have required," says Maudsley, "a change in our conception of solid matter. Instead of the notion of inert, impenetrable matter, we must substitute the idea of matter which in its colloid state is penetrable, exhibits energy, and is widely susceptible to external agents. This sort of energy is not a result of chemical action, for colloids are singularly inert in all ordinary chemical relations, but is a result of its unknown molecular constitution; and the undoubted existence of colloidal energy in organic substances, which are usually considered inert and called dead, may well warrant the belief of its larger and more essential operation in organic matter in the state of instability of composition in which it is when under the condition of life. Such energy would then suffice to account for the simple uniform movements of the homogeneous substance of which the lowest animal consists, and the absence of any differentiation of structure is a sufficient reason for the absence of any localization of function and of the general uniform reaction to local impressions." Graham himself says: "The colloidal state may be looked upon as the probable primary source of the force appearing in the phenomena of vitality." The colloidal condition is the dynamical state of matter; the crystalloidal the static. The former, which is the rule in the organic kingdom of nature, is the exception in the inorganic. Aluminum and ferric hydrates, silicic acid, and a few other inorganic substances, exist in the colloid condition. From analogy there would seem to be but little doubt that the colloid state of these bodies differs from their crystalloid state merely in the size of the molecule. In other words, opal, which is colloid silica, is a polymer of quartz. If this theory be true, there can be no doubt of the vastly greater complexity of a colloidal proteid molecule than of a crystalloid one. Now, it is a very significant fact, in this connection, that not a single organic colloid has ever been synthesized. Gelatine, which is one of the best examples of a colloid, has a comparatively simple structure. And, although Gibbs showed, many years ago, that gelatine was probably an amido-derivative of the sugar group, yet no inverse process has yet given us this substance. That matter in the crystalloid and the colloid forms may be chemically identical, differing only in the size of its molecule, may
