The liver, our largest gland, has numerous and varied functions, and hence a most complex physiology. It plays an important rôle in the metabolism of carbohydrates, proteins and fats; it forms bile salts and helps form and excrete bile pigments; it modifies various substances produced in the body in such a way as to make these substances more easily handled and less harmful to the body; it performs detoxication work.
An exact determination of the condition of the liver in any normal or pathologic case would, of course, presuppose a complete understanding of its performance of all these functions. But since this is quite impracticable, one would rather attempt the study of merely one or two functions, which while sufficiently easy of determination, and this by a test not too cumbersome for manipulation, would yet give a fairly good estimate of the general functional condition of the organ. Several such