We must again emphasize the great importance of carbohydrate food; there is a far larger amount of starchy food consumed than of any other foodstuff, and it is more readily available as a source of energy. Its presence in the blood, in the form of sugar, is constantly demanded, but it must be kept within the proper limits for the uses of the different tissues and organs of the body. The liver serves as an effective regulator, maintaining, in spite of all fluctuations in the supply and demand, a definite percentage of sugar such as is best adapted to keep the tissues of the body in a normal and healthy condition. This regulation by the liver is rendered possible through the ability of the hepatic cells to transform the sugar brought to the gland into glycogen, so-called animal starch, which is stored up in the liver until such time as it is needed by the body. The process is one of dehydration, the reverse of what takes place in the intestine when ordinary starch is converted into maltose and dextrose. The efficiency of this regulating mechanism depends also upon the ability of the liver to transform glycogen into sugar, presumably through the agency of an enzyme in the hepatic cells. Hence, glycogen may be looked upon as a temporary reserve supply of carbohydrate, manufactured and stored in the liver during digestion, when naturally large amounts of sugar are passing into the portal blood, and to be drawn upon whenever from any cause the content of sugar in the blood threatens to fall below normal. Obviously, there must be some delicate machinery for the adjustment of these opposite changes in the liver, and we may well believe that it is associated with the composition of the blood itself, which in some fashion stimulates and inhibits, as may be required, the functional activity of the liver, or its component cells. In any event, we have in this so-called glycogenic function of the liver a most effective means for accomplishing the complete and judicious utilization of all the sugar formed from the carbohydrates of the food, after it has once passed beyond the confines of the alimentary tract into the blood; preventing all loss, and at the same time guarding against all danger, from undue accumulation of sugar in the circulation. We see, too, how wise the provision that all sugar should pass from the alimentary canal into the portal circulation and not by way of the lymphatics, since by the latter channel the regulating action of the liver would be mainly lost. Further, recalling how soluble and diffusible sugar is, we may well marvel that it practically all passes from the intestine by way of the blood, and escapes entry into the lymphatics. Surely, this marked shunning of the other equally accessible pathway affords a striking illustration of selective action such as might be expected in a physiological process, but not in harmony with the ordinary physical laws of osmosis or diffusion. In conformity with this statement, it may