The difficulties encountered in any functional test studies are particularly accentuated in those concerned with the liver. This is largely due to the fact that nature has entrusted to the liver a multiplicity of functions not equaled by any single organ. These numerous activities, widely dissociated in character, give rise to the necessity for the many liver tests that have been devised. The application of these tests is beset with further difficulties dependent on the peculiar physiologic activity of the liver. The continued functioning of this organ being vitally necessary,1it has been endowed with an adequate reserve2and a markedly high regenerative capacity. Some idea of the regenerative ability of the liver cells may be obtained from the experiments of Mann and Bollman,3who found that the removal of 70 per cent of the liver of the normal dog was followed in a few weeks by