464 THE ALCOHOLS. 



tions, namely as dextrorotatory sarcolactic acid, paralactic acid, a metabolic 

 product of muscle and also in the thymus and thyroid glands ; it develops also 

 from the action of bacteria on grape-sugar, and as ordinary optically inactive or 

 fermentation-lactic-acid, which is present in the gastric juice, in sour milk, sour- 

 crout, sour pickles, and can also be obtained from sugar by fermentation. (2) The 

 isomer ethyl ene lactic acid is likewise present in muscle in small amounts. 



(rf) Leucic acid, oxycaproic acid, C 6 H 12 O 3 , does not occur independently, but 

 only as a derivative, namely as leucin, amidocaproic acid, as a metabolic product 

 in. certain tissues, as well as a product of pancreatic digestion. By treatment 

 with nitrous acid leucic acid can be produced from leucin, and glycolic acid from 

 glycin. 



4 . A cids of the oxalic-acid or succinic-acid series , with the formula C n H 2n - 4 O 2 (O H) 2 , 

 dibasic acids, which develop from fatty acids and glycolic acids as completed 

 oxidation-products by taking up oxygen and giving off water. Their development 

 from bodies rich in carbon, particularly fats, carbohydrates and proteids, is, there- 

 fore, noteworthy. 



(a) Oxalic acid, C 2 O 2 (OH) 2 , results by oxidation from glycol, glycin, cellulose, 

 sugar, starch, glycerin and many vegetable acids, and occurs normally in the 

 urine in combination with calcium. 



(6) Succinic acid, C 4 H 4 O 2 (OH) 2 , has been found by some in small amounts 

 in dead animal tissues and fluids, urine, echinococcus-fluid, hydrocephalus-fluid, 

 hydrocele-fluid. It is present in large amount in the urine of the dog after a 

 diet of fat and meat, in the urine of the rabbit when fed with carrots. It is gen- 

 erated by micro-organisms and is wanting in fresh, living tissues. It develops in 

 small amounts in the process of alcoholic fermentation. 



5. The cholalic acids are present in bile and in the intestine. 



6. Aromatic acids, containing the benzol-nucleus: benzoic acid (phenylformic 

 acid) occurs in the urine in conjunction with glycin as hippuric acid. 



THE ALCOHOLS. 



Alcohols are bodies that develop from carbohydrates by the substitution of 

 hydroxyl (HO) for one or more atoms of hydrogen. They can also be viewed 

 as water, }O, in which half of the hydrogen is replaced by a CH-combination. 

 Thus, for instance, C 2 H 6 , ethyl hydrid, is transformed into C2 g 5 }O, ethyl-alcohol. 



(a) Cholesterin, cJ^j-O, is a levorotatory alcohol that occurs in blood, yolk' 

 brain and bile, and," besides, quite generally in vegetable cells. It is present 

 also in tissues of man and animals containing keratin. Liebreich considers choles- 

 terin as a necrobiotic fat. By oxidation cholesteric acid (C 8 H 10 O 5 ) is developed 

 from cholesterin, appearing also as an oxidation-product of cholic acid. 



( OFT 



(6) Glycerin, C,H,O^ OH, is considered as a triatomic alcohol. It occurs in 



I OH 



combination with fatty and oleic acids in neutral fats. It is formed in the process 

 of pancreatic digestion by decomposition of the neutral fats. It is developed 

 in small amount as a result of the fermentation of fats in the intestine, as well 

 as in the process of alcoholic fermentation. 



(c) Phenol (phenylic acid, carbolic acid, oxybenzol). 



(d) Pyrocatechin (dioxybenzol) . 



(e) The sugars may be considered advantageously in connection with the 

 alcohols, as they behave like polyatomic alcohols. Their exact constitution is as 

 yet unknown. The sugars form, together with a series of closely related bodies, 

 the large group of carbohydrates, which will be considered collectively. Although 

 many of these do not occur in the animal body, their consideration is justified by 

 the fact that they occur largely as constituents of vegetable food. 



THE CARBOHYDRATES. 



These bodies occur in the animal and vegetable kingdoms and have received 

 their designation because they contain in their molecules, in addition to at least 

 six atoms of C, the atoms of H and O always in the proportions present in water, 

 namely, H 2 O. All are solid, chemically indifferent, without odor. They either 

 have a sweet taste (sugars) or may at least be readily transformed into sugar 

 by the action of dilute acids. They deflect the ray of polarized light either to 



