CHEMICAL BASIS OF THE ANIMAL BODY. 1277 



This acid forms salts of which that with barium crystallizes 

 readily and in a very characteristic triangular form. 



Apart from its crystalline form and that of its barium salt 

 this acid may be readily recognized by the following reaction. 

 When heated on a water bath with hydrochloric acid and 

 chlorate of potash and evaporated to dryness a reddish residue 

 is obtained which turns at first to a brownish green on the addi- 

 tion of ammonia and finally to an emerald green. 



The amount of kynurenic acid in the urine is increased on 

 the ingestion of isatin, a product of the oxidation of indigo. 

 Under ordinary conditions its amount in this excretion is de- 

 pendent upon the nature of the food supplied to the animal, 

 being greatest under a proteid diet, and is not related to the 

 occurrence or absence of putrefactive processes in the alimentary 

 canal. 



5. Inosite. C 6 H 12 6 + 2H 2 0. [CH . OH] 6 . 



This substance has the same percentage composition as a 

 sugar and possesses a distinctly sweet taste, in virtue of which 

 properties it appears to have been usually classed with the 



Fig. 229. Inosite Crystals. (After Kiihne.) 



carbohydrates. It does not however yield any of the reactions 

 most typical of this class of substances ; for instance it exerts 

 no rotatory power on polarized light, does not reduce metallic 

 salts, does not undergo alcoholic fermentation and does not 

 react with phenyl-hydrazine. On account of these peculiarities 

 the view was long ago expressed that it is not a carbohydrate 

 at all, and it has more recently been shewn to belong to the 

 benzene series. Structurally it may be represented by a closed 

 ring of six CH . OH groups. 



Inosite occurs but sparingly in the human body ; it was 

 found originally in the muscles. It is found in the lungs, 

 kidneys, spleen, liver, and brain, and occurs also in diabetic 



