PATHOGENIC BACTERIA 251 



Cholin is a substance which is present normally in all cells. 

 It forms the nitrogen portion of the lecithin molecule. The 

 source of this ptomain in decomposing protein material is 

 therefore evident. It is stated by various writers that it is 

 broken down in the animal body especially when nervous tis- 

 sue, which is rich in lecithin, is disintegrated. Cholin is said 

 to be present in the cerebro-spinal fluid and in the blood in 

 certain degenerative nervous diseases. For example, it has 

 been reported in the blood in cerebral syphilis, epilepsy, and 

 dementia paralytica. Cholin is only slightly toxic, but the 

 next member of the group, neurin, into which cholin can be 

 transformed, is very toxic. Wells suggests that intoxications 

 in the gastro-intestinal tract which are often ascribed to " food 

 intoxications " may be due to cholin being split off from the 

 lecithin of the food by the action of saprogenic bacteria and 

 the cholin thus formed being changed into neurin which, when 

 absorbed, gives rise to intoxication. 



Cholin and neurin are closely related in structure and physi- 

 ological action to muscarin, an alkaloidal substance first 

 derived from mushrooms. A ptomain identical with muscarin 

 has been isolated from decomposing fish, and the name mus- 

 carin has also been applied to it. Neurin and muscarin are 

 very poisonous ptomains. Betain, the last member of the 

 group, is only slightly toxic. It is also derived, for the most 

 part, from the lecithin of the cells. 



Toxins. As has been stated, certain bacterial cells have 

 the power of secreting poisonous synthetic products into the 



