could still be reconciled to these views as necessarily modified subsequently to Wöhler's discovery. The compounds thus formed artificially were still of comparatively simple structure; and, in the numerous transformations effected by Berthelot, in no case was the passage from a compound of a lower to one of a higher order. Marsh-gas, methyl alcohol, and formic acid, each contained but one atom of carbon; ethylene, ethyl alcohol, and acetic acid, each contained two atoms of carbon. Surely the vital force alone could build up more complicated bodies.
Not so. The series of advances in the new doctrine, thus so propitiously begun, did not stop. New methods of investigation were introduced. Questions of a different character were put to chemical substances, and answers were not wanting. The interest in chemical science increased, and the army of those who were to carry it forward also increased. The growth of the science became proverbially rapid, and, during the excitement attendant upon this development, the last of the old landmarks between inorganic and organic bodies was swept away; vital force, as far as it was directly concerned in the formation of organic bodies, lost prestige. Both classes of bodies were found to be subject to the same fixed laws, A chemical substance is a chemical substance, look at it as we will. Its constituents, in one case as in the other, are bound together by chemical affinity, simply and alone. Whatever the conditions may be which surround the formation of organic bodies in the animal or vegetable organism, the final combination of the atoms, necessary to the formation, is brought about by chemical affinity. Although we cannot reproduce these conditions outside of the body, we can in so far imitate them that the same kind of combination will take place. We have a-t our command at present many means for the building up of the most complicated organic bodies from the simplest. Some of these are easily understood, and were discovered as the result of strict logical deduction; others are still inexplicable, and were discovered by accident. We can pass readily from one hydrocarbon to another, adding carbon-atoms to an extent which, theoretically at least, is unlimited; from one acid to another of higher order; from alcohol to alcohol; from alcohol to acid; from acid to hydrocarbon; from hydrocarbon to acid, through all the normal series of organic compounds. So great is our power in this direction, that it is possible to produce any member of any regular series of organic compounds from marsh-gas as a starting-point, or from any other member whatsoever. But marsh-gas can be indirectly produced from its elements, carbon and hydrogen; hence, we have the possibility given of preparing artificially by far the greater number of organic compounds. This number includes many of those substances which are formed in the animal or vegetable organism.
The formation of urea and formic acid has been alluded to. With-
