proteins of a definite kind, and in obviously definite quantities, are always circulating in the blood, and the amount of carbohydrates also varies only within narrow limits, the fats behave quite differently. The amount of fats in the plasma varies within a wide range. After a meal rich in fat we find so much fat in the blood plasma that it may be seen with the naked eye; and, if we let the plasma stand, the fat separates out directly and appears as a layer on the surface of the plasma. A short time after the meal the fat disappears again from the blood. It is transmitted to the different cells of the body, and is there used up, transformed, or even directly stored as reserve material. It seems that the blood, with every increase in the amount of fat, responds with an increase of lipase. From the point of view we have laid down the excess of fat has to be considered as being out of harmony with the plasma. Only in an animal whose stomach is completely empty do we find no, or very little, capacity for splitting fats. After a meal rich in fat active lipase can be demonstrated in the blood. It can also be shown that during a more or less prolonged hunger period the splitting power of the blood increases. This corresponds with the experience that, during fasting, an active transportation of material is going on. In many cases of fasting large quantities of fat could be shown to be present in the blood. If a fat be introduced that is
