BASES DERIVED FROM THE PROTEINS 239 



which sets free a very toxic substance from the protein of a 

 subsequent injection. Whether this toxic substance is simply 

 /3-iminazolylethylamine, it is as yet impossible to say ; the 

 phenomenon appears to be more complicated. Nevertheless, 

 even if we do not go so far as Kraus, who in a recent paper 

 seems to favour this identity, we may well admit that the 

 parallelism between the two kinds of poisoning is very sug- 

 gestive and such as to support the view that anaphylactic 

 shock is due to some simple toxic fission product of protein. 



Ptomaines 



The scientific use of this term, introduced by Selmi, is 

 being more and more restricted on account of the ambiguity 

 attached to it. In 1870 and 1871, in the course of a medico- 

 legal examination, Selmi separated from human corpses certain 

 bases which gave the ordinary alkaloidal tests ; he was unable 

 to identify the bases with any of the known vegetable alkaloids. 

 Soon afterwards Gautier showed that substances of a basic 

 nature are produced during the putrefaction of proteins. The 

 early investigators of these bases, not unnaturally, were 

 influenced a good deal by previous work on plant alkaloids ; 

 the methods used in isolating the animal bases were at first 

 simply modifications of those already in use and were founded 

 on the solubility of the bases in ether, chloroform, amylic 

 alcohol, etc. When Brieger, in 1883, used other methods, such 

 as, for instance, precipitation by means of mercuric chloride, 

 he was at once able to isolate ptomaines which had been over- 

 looked previously on account of their very slight solubility in 

 organic solvents. The use of the older methods devised by 

 Stas, Otto and Dragendorff chiefly led to the isolation of 

 monamines free from oxygen, such as phenylethylamine, which, 

 however, was described erroneously as collidine. The tendency 

 to compare putrefaction bases with plant alkaloids like confine 

 and nicotine has in some cases led to their conception as 

 pyridine derivatives but as no known protein constituent 

 contains a pyridine nucleus, it is difficult to account for the 

 formation of such bases. If pyridine derivates are indeed formed 

 by the action of bacteria on proteins, the action must be of 

 a very different nature from simple changes such as that of 

 decarboxylation which have been discussed in this article and 



