274 NITROGEN BASES 



alkaloids by plants is merely due to the inability of such 

 plants to get rid of their nitrogenous products of metabolism 

 by any other means than by converting them into alkaloids, 

 which, though poisonous to animals, are not toxic to the 

 plants themselves. 



PTOMAINES. 



Associated with the simplest form of plant life, namely, 

 bacteria, a number of different basic substances are found, 

 some of very simple constitution, such as methylamine, 

 CH3NH2, dimethylamine,(CH3)2NH, trimethylamine, (CHgjaN, 

 putrescine, NH^CCHa^NHg, cadaverine, NH^CCHa^NH,, and 

 others rather more complex, such as choline, muscarine, 

 neurine, coUidine, etc., and some of unknown constitution, 

 such as mydaleine and sepsine. These substances are known 

 as ptomaines,* from the fact that they are usually associated 

 with decomposing flesh ; some of them, such as putrescine and 

 cadaverine, are practically non-poisonous, while others are 

 highly toxic, producing increased salivation, diarrhoea, vomit- 

 ing, etc. 



On the whole, however, it is at least doubtful whether the 

 manifestations of ptomaine poisoning are to be attributed 

 entirely to these substances ; it would seem more likely that 

 they were largely due to bacterial toxins, a class of substance 

 related to the albumoses, which have the power of inducing 

 the formation in the blood of antibodies, or, as they are 

 better called, anti-toxins. Similar toxins or toxalbumins also 

 occur in certain of the higher plants, as, for example, abrin, 

 obtained from Abrus precatorius, and ricin, which occurs in 

 Ricinus. 



The so-called ptomaines are all decomposition products of 

 the complex nitrogenous substrate upon which the moulds or 

 bacteria are growing, but are not actually found within the 

 organisms themselves. 



In the higher forms of plant life, on the other hand, these 

 bases are actually secreted by and stored up in the plants ; 

 the substance muscarine, for example, occurring in the fungus f 

 Amanita vmscaria. 



*From the Greek word irTwixa, meaning corpse. 



t The same remark, of course, applies also to the Angiosperms, which con- 

 tain their alkaloids stored up in ditTerent parts of their structure. 



