290 ISIDOR GREENWALD 



it might be very difficult to obtain evidence of the nature, or even existence, 

 of the anomaly. But if this were not the^case, the condition would be 

 revealed as in the previous instance. 



It will, perhaps, serve to make this a little clearer to remind the reader 

 that the excretion of acetone, aceto-acetic acid and l^-hydroxybutyric acid 

 in diabetes and other conditions is due to disturbance of fat metabolism 

 which belongs in one, or both, of these last two categories. 



4. Other abnormalities that cannot be so readily classified. Such are 

 found in connection with disease of the thyroid, adrenal and pituitary. 

 Some such disorder of carbohydrate metabolism is probably concerned in 

 the etiology of some kinds of obesity. 



So little is known of the intermediate stages of the katabolism of 

 carbohydrate that it is difficult to determine any deviation from the normal 

 in this regard. The presence of lactic acid in the urine in acute yellow 

 atrophy of the liver, phosphorus poisoning, etc., is unquestionably an 

 example of either the second or third of these classes of abnormalities. 

 The occurrence of many severe disturbances within either of these classes 

 is made somewhat improbable by the finding of normal respiratory 

 quotients in a large number of pathological conditions (Barr and Du Bois, 

 Coleman and Du Bois(6), Du Bois(6), Meyer and Du Bois, 'Murphy 

 Means and Aub, Peabody Meyer and Du Bois). But it should not be 

 forgotten that slighter anomalies of metabolism would not betray them- 

 selves by changes in the respiratory quotient. They would, however, be 

 expected to affect the carbon elimination in the urine. It is quite possible 

 that studies of the carbon distribution, or partition, in the urine, particu- 

 larly after removal of most of the nitrogenous constituents with acid 

 mercuric nitrate or similar reagent, would have results as interesting as 

 those that have been obtained in studies of the nitrogen partition. 



The known disorders of carbohydrate metabolism are then chiefly of 

 the first class, those that manifest themselves by the excretion, in the 

 urine, of carbohydrate in quantities exceeding the normal. That carbo- 

 hydrates are normal constituents of urine may be regarded as established, 

 though their nature is not definitely known. Their demonstration requires 

 special methods, and their presence is not likely to be mistaken for the 

 occurrence of a pathological condition. (Benedict, Osterberg and Neu- 

 wirth.) 



Note on the Chemical Nature of the Carbohydrates 



Before discussing the individual melliturias, it may be well to consider 

 for a moment the chemical nature of the carbohydrates. They are hy- 

 droxyaldehydes and ketones. Each carbon atom, but one, is combined 

 with an alcohol, or OH group. The exception is either at the end of the 

 chain and in an aldehyd, or CHO group, or is next to the end and in a 



