VITAL PHENOMENA OF BACTERIA. 69 



were looked upon as the specific bacterial poisons, while 

 others were harmless. The poisons are particularly in- 

 teresting, since they may be present in the decomposing 

 cadaver (hence the name ptomai'n), and, in consequence, 

 have to be taken into consideration in questions of legal 

 medicine. They may be formed also in the living 

 human body, and, if not made harmless by oxidation, 

 may come to act therein as self-poisons or leuconiai'ns. 

 They are now known not to be the substances to which 

 are due the specific poisonous effects of bacteria which 

 are designated as toxins, and have entirely different 

 characteristics. 



Many ptomaios are known already and the empirical 

 formula of each made out, and among them are some 

 whose exact chemical composition is established. The 

 first of these bodies to be separated was colloidin 

 (C 8 H U N), obtained byNencki from putrefying gelatin. 

 Another, trimethylamin (C 3 H 9 N = (CH 3 ) 3 N), gives an 

 odor like herring-brine. Especially interesting is the 

 substance cadaverin, which was separated by Brieger 

 from portions of decomposing dead bodies and from 

 cholera cultures, by reason of the fact that Ladenburg 

 prepared it synthetically and showed it to be penta- 

 methylenediamin [(NH 2 ) 2 (CH 2 ) 6 ]. The cholin group 

 is particularly interesting. Cholin itself (C 5 H 15 NO 2 ) 

 arises from the hydrolytic breaking-up of lecithin, the 

 fatty substance found in brain tissue and other nervous 

 tissue. 



By the oxidation of cholin there can be produced the 

 non-poisonous betain or trirnethylglycocoll occurring in 

 beet-juice, and the highly toxic muscarin, found by 

 Schmiedeberg in a poisonous toadstool and by Brieger 

 in certain decomposing substances : 



