PRODUCTS OF META50LISM 171 



bacteria. Another group are the amins. The simplest amins are 

 the methyl-amins, of which the tri-methylamin (CH3)3N is produced 

 by several bacteria. The fishy odor of the brine of salted herring is 

 largely due to this compound. In this group belong also a large number 

 of the so-called ptomains. 



The ptomains (page 491) are alkaloid-Hke bodies of basic character 

 and of more or less well-known structure. Some of them are notorious 

 for being very strong poisons, while others are quite harmless. These 

 bodies are called ptomains because they were first discovered in 

 putrefying corpses. The best-known compounds of this character 

 are the putrescin or tetra-methylen diamin [NH2(CH2)4NH2] and the 

 cadaverin or penta-methylen-diamin [NH2(CH2)6NH2], which can 

 scarcely be considered poisonous. The methyl-guanidin 



NH2 



HN = c/ 



/ , NHCH3 



may be mentioned as an example of a very poisonous ptomain. Another 

 poisonous ptomain is the neurin CH2 = CH — N(CH3)30H which has 

 been.^und frequently as a product of putrefaction. 



Ammonia is the end product of protein decomposition, as far as 

 the nitrogen-containing fragments of the protein molecule are con- 

 cerned. That ammonia is formed by many bacteria, is well known. 

 In some decaying proteins, . e.g., in old Camenbert cheese, ammonia 

 can be very easily detected by the smell. As all proteins contain 

 many amino-groups as well as acid-amid groups, it is easily understood 

 how the ammonia originates through the hydrolysis of protein. In 

 the complete oxidation of proteins, the nitrogen is always left as NHs 

 or (NH4)2C03 respectively, never, so far as known, in any other 

 form. ' No bacterium is known to produce urea, as most of the higher 

 animals do. 



In the products of protein degradation mentioned above only 

 those compounds have been considered which contain nitrogen, • It is 

 quite evident, however, that in the cleavage of the large and complex 

 protein molecules, certain parts of the molecule will contain no nitrogen. 

 Many organic acids, like acetic, butyric, capronic, benzoic and phenyl- 

 acetic acids are quite generally found among the products of putre- 



