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ratory act than that which we now possess—for we speak very much more as Servetus did than could be desired in the nineteenth century. We deal with little else than fuliginous vapour, though our acquaintance with gaseous chemistry enables us to call it by another name.
There is scarcely anything more remarkable within the whole range of physiology than the great and rapid change effected by respiration. When we consider what are the contents of the right auricle of the heart—how it can scarcely be said to contain blood—it is indeed surprising that the wondrous fluid, the great builder of the organism, can be so rapidly formed from such materials.
Here we find chyle and lymph freshly mixed with venous blood poured into the cavity. These fluids have now to mix with blood from the hepatic veins, charged with a peculiar animal principle, and these materials are to be worked up into something fitted for circulation through the lungs, where, by contact with atmospheric air, a fluid is elaborated having a definite and fixed constitution; definite in the quality, and fixed in the proportion of its constituents.
