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 ptomain), 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 leucomains. 
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 ptomains 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,H,,N), obtained by Nencki from putrefying gelatin. 
Another, trimethylamin (C,H,N = (CH,),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,),(CH,),]. The cholin group 
is particularly interesting. Cholin itself (C,H,,NO,) 
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 trimethylglycocoll occurring in 
beet-juice, and the highly toxic muscarin, found by 
Schmiedeberg in a poisonous toadstool and by Brieger 
in certain decomposing substances : 
