METABOLISM 213 



excreted as hippuric acid. From these facts it is evident that 

 the side chains are oxidized so that not one carbon atom, but 

 two are removed at each step. 



Thus it is believed that the fatty acids from the fats also are 

 oxidized two carbon atoms at a time, the final products normally 

 being converted completely into carbon dioxide and water. The 

 acetoacetic acid CH 3 CO CH 2 COOH, -oxybutyric CH 3 

 CHOH CH 2 COOH and acetone which appear in the urine in 

 the advanced stages of diabetes, when the organism is so severely 

 affected that its powers of oxidation are impaired are believed to 

 be largely a product of the incomplete oxidation of fatty acids, 

 though acetoacetic has been shown to arise also from certain of 

 the amino acids. 



Interesting work has recently been published by Shaffer on 

 the conditions governing the appearance of acetone bodies in 

 the urine. It has become evident that the proper burning of 

 fatty acids in the body is influenced by the presence of glucose. 

 Since fatty acids are a source of the acetone bodies, as are also 

 certain of the amino acids, Shaffer calls these compounds t ' keto- 

 genetic" (Symbol K). Glucose, both that from the food carbo- 

 hydrates and from amino acids or other sources he calls "anti- 



TT7- 



ketogenetic" (Symbol A). When the value-r-=2 or more, 



A. 



acetone bodies appear in the urine. A method has been devised 

 on this basis whereby it is possible to calculate the amount of 

 carbohydrate it is necessary to supply to a diabetic to prevent 

 the excretion of acetone bodies in the urine. 



Metabolism of Inorganic Material. The metabolism of inor- 

 ganic material assumes an aspect somewhat different from that 

 of the organic substances, for the reason that inorganic sub- 

 stances are not disintegrated or " burned " in the organism, and 

 thus are not sources of energy. There is, of course, more or less 

 interchange of radicles, and to a certain extent inorganic sub- 

 stances are built into compounds of organic nature. But quite 

 aside from this, inorganic materials play a very important part 

 in metabolism. Numerous chemical reactions in the body are 



