Clinically, the earliest symptom to raise suspicion, is the reappearance of vomiting at a time when one would expect such trouble to have abated, usually twenty-four or thirty-six hours after operation. Within a few hours, the nature of the vomit changes from the usual bilious stomach contents, and shows obvious evidence of the presence of _altered blood_. The pulse and temperature begin to rise, the countenance assumes an anxious look. A trace of jaundice is usually present. The nervous system becomes affected as shown first in restlessness, and later, delirium. Every degree of this condition is possible, but a very large proportion of recognisable cases pass into coma, and death supervenes within a few days, sometimes less. Investigation into such cases has shown that the essential underlying condition is an acidosis closely allied to that seen in diabetic coma. The breath has the peculiar sweetish aroma of acetone, and acetone, diacetic acid, and B. oxybutyric acid successively appear in the urine. Post-mortem, the most striking change found is a profound fatty degeneration of the liver, the cells of which are disintegrated as in acute yellow atrophy. It is obvious from the foregoing that there is present a very remarkable abnormality of metabolism. Mr Rendle Short, in his admirable book, _The New Physiology in Surgical and General Practice_, gives the following explanation of the condition:-- “The physiological process of dealing with fat is to resolve it into carbon di-oxide and water. If we make a pound of fat into tallow candles and burn it, we shall obtain carbon di-oxide and water, and a certain amount of heat will be evolved. If the pound of fat is eaten and absorbed by a man or an animal, it will be burnt to the same end products, and the same amount of heat will be given out. But in certain circumstances, an abnormal mode of breaking down is followed, and there are produced, first B. oxybutyric acid, then diacetic acid, and finally acetone. If this takes place on a large scale, the conversion into acetone fails to keep pace with the production of acids. Therefore first acetone appears in the urine, then diacetic acid, and finally oxybutyric acid; the last may rise rapidly to an enormous figure: 30, 50, or even 180 grams may be passed daily.” Later in the same chapter, Short propounds the question as to what are the special circumstances in which the breaking down of fat deviates from its normal course, and follows this dangerous route. The answer is, he says, quite definite and decisive. When the tissues are unable to obtain sugar from the blood, fat is broken down _via_ these dangerous acids to acetone, instead of to carbon di-oxide and water. Such an inability on the part of the tissues to obtain sugar arises under several conditions:-- (_a_) In diabetes, where sugar though freely present in the blood cannot, for some reason still not clearly known, be assimilated by the tissues.