376 THE FINAL DECOMPOSITION OF FOODSTUFFS IN THE BODY 



In diabetes there appear in the urine besides sugar the so-called acetone 

 bodies: j8-oxybutyric acid, aceto-acetic acid and acetone, the relations of which 

 to each other are evident from the following formula: 



OH. CH, OH. 



CH.OH CO CO 



CH, OH, CH, 



COOH COOH <*XS*.> 



0-Oxybutyric acid Aceto-acetic acid 



With the exception of acetone, which is eliminated in small quantities under 

 physiological conditions also, these compounds never, so far as known, appear 

 in the normal urine; from which it follows that diabetes must be intimately 

 connected with deep-seated changes in the general metabolism. 



Most of the carbohydrates pass through the stage of hexoses before they 

 are further decomposed in the body. Like the other foodstuffs they are not 

 immediately oxidized to their end products, but pass through more or less 

 complex groups before being eliminated as carbon dioxide and water. To 

 these intermediary products belong: glycuronic acid CHO.(CHOH) 4 .COOH, 

 which in its turn can be transformed into oxalic acid in the body ; sarcolactic 

 acid ( ?) ; and ethyl alcohol. It cannot be decided yet from the observations 

 thus far reported whether sugar always breaks up in the same way, or whether 

 under different circumstances and in different organs it runs through different 

 cleavage products. 



3. THE DECOMPOSITION OF FAT 



Fat eaten in excess is directly deposited as such in the fat cells. How it 

 is transported and how deposited is not yet entirely clear. Metzner in his 

 investigations of this question was unable to find anywhere a depository 

 where fat was entering cells in corpuscular form; he never found in the 

 immediate neighborhood of cells any fatty granules similar to those found 

 inside of the cells. Moreover, in the very early stages of deposition, fat is not 

 laid down in the form of granules, but in the form of minute vacuoles which 

 expand and enlarge from day to day (cf. page 304). These facts are inter- 

 preted by Metzner and Altmann to mean that fat is added to the cells only 

 in the form of soluble cleavage products (fatty acids), which are synthesized 

 again into neutral fats in the cell. It is not unlikely that fat is again split 

 up when it leaves the fat cells and is carried to the different organs in 

 soluble form. 



For the purpose of obtaining some light on the oxidation of fats in the 

 animal organism, Pohl has studied the behavior in the body of those inter- 

 mediary cleavage products which theoretically may be expected to appear in the 

 normal course of fat destruction. Thus, if the series of substances which can 

 be formed in the oxidation of highly complex fatty bodies i. e., fatty acids and 

 carbohydrates be arranged in order, it is seen that relatively simple inter- 

 mediary compounds precede the formation of CO 2 , alike for the most widely 

 different bodies. If now it can be shown by experiments on animals that some 



