THE PTOMAINS. 91 



On decomposition with strong hydrochloric acid indican is accord- 

 ingly decomposed into sulphuric acid and indoxyl, which latter can 

 then be oxidized to indigo-blue : 



co C0 



2 = 



Indoxyl. Indigo-blue. 



On reduction indigo-blue is transformed into indigo-white, 

 C 8 H 6 NO, which, when boiled with zinc and water, then further 

 yields indol : 



C 8 H 5 NO + H ^CsHgNO. 



C 8 H 6 NO + 3H r- C 8 H 7 N + H 2 O. 



Animal indican, however, must not be confused with vegetable 

 indican, which is a glucoside, and yields indigo-blue and indiglucin 

 on hydrolytic decomposition : 



C 26 H 31 NO 17 -f- 2H 2 O = C 8 H 5 NO - 

 Vegetable indican. Indigo-blue. Indiglucin. 



A small amount of skatoxyl, indoxyl, and phenol is also eliminated 

 in the urine, in combination with glucuronic acid, as skatoxyl, 

 indoxyl, and phenol glucuronates, respectively. This acid may be 

 derived from glucose by the substitution of one atom of oxygen for 

 two atoms of hydrogen, and is accordingly represented by the 

 formula COOH.(CH.OH),.COH. It is possible, however, that glu- 

 curonic acid may also be derived from chondroitin-sulphuric acid, 

 which is normally found in cartilage, and, as a matter of fact, we 

 have seen that through a series of simple reactions glucuronic acid 

 can be obtained from this source. On oxidation it is transformed 

 into saccharinic acid, the relation of which to glucose has already 

 been considered. 



THE PTOMAINS. 



The term ptomain was originally applied by Selmi to certain 

 alkaloidal bodies which are formed during the process of albu- 

 minous putrefaction. Gautier then extended its use to include all 

 those alkaloidal substances which result from anaerobic fermenta- 

 tion, as also those which are formed in the tissues of the higher 

 animals in the absence of air, or in the presence at least of an insuf- 

 ficient supply of oxygen. In contradistinction to these substances, 

 Gautier terms those alkaloidal bodies which are formed during the 

 normal and aerobic life of the tissues leucomains. Under this 

 latter heading, as has been seen, he comprises the nucleinic bases 

 and the kreatins. Both classes of substances are of special interest 

 to the physician, as their formation or undue accumulation in the 

 body may give rise to serious disturbances. This is true more 

 particularly of the ptomains, some of which are extremely toxic. 



Gautier divides the ptomains into acyclic and cyclic ptomains, 



