From study of 50 cases of old age, including 26 of healthy old men, the remainder being more or less pathological, Marshall concludes that 5 types of glucose-tolerance curves occur in healthy old people: the normal adult; the storage defect; the "lag"; the "flat"; and the typical diabetic types. The frequency with which each of these types occurs has been indicated, and the storage-defect type has been shown to occur most frequently. The "lag" type of curve occurs in 25% of healthy cases, and this is probably a much higher incidence than is found in the normal adult. The same 5 types of curve occur also in the group of unhealthy cases, but the incidence of each type is altered and the "diabetic" type preponderates, and is found in as many as 50% of cases. It is concluded that most diseases (and particularly chronic bronchitis), when they occur in old age, have a deleterious effect on the sugar tolerance. No relation can be traced between the height of the blood-pressure, and either the sugar content of the blood, or the renal threshold. The renal threshold in healthy old age is generally raised, and may be taken to be in the neighbourhood of 0.2%.