CHAPTER IV. 



CHEMICAL PRODUCTS OF BACTERIA. 



The products of the metabolism induced by bacteria may be divided 

 into three classes : (1) ptomaines or alkaloids ; (2) albumoses or tox- 

 albumins ; and (3) enzymes. Alkaloids and albumoses are directly 

 poisonous ; enzymes or ferments are harmless except in the presence 

 of proteids, which they are capable of transforming into poisonous 

 albumoses. 



Ptomaines and Tox- Albumins. 



The study of these products may be said to date back to 1822, 

 when Gaspard and Stick found an intensely poisonous principle 

 in cadaverous extracts. In 1856 Panum discovered a poisonous 

 substance in putrid ilesh; and in 1863 Bergmann and Smiedeberg 

 found a nitrogenous crystallisable substance in putrid beer which 

 they named sepsin. In 1872 Gautier found that the decomposition 

 of fibrine led to the formation of various complex alkaloidal sub- 

 stances, and in 1875 Richardson obtained in pyaemia an alkaloid, 

 septin. This subject, however, received most attention from the 

 classical researches of Selmi, the Italian toxicologist. Selmi, in a 

 celebrated poisoning case, demonstrated the presence of an alkaloid 

 as the result of post-mortem changes. Similar substances were 

 found in alcohol in which morbid specimens had been preserved. 

 Thus the researches of Gautier and Selmi established the fact that 

 aJbuminoid material tindergoing decomposition leads to the forma- 

 tion of cadaveric alkaloids. These animal alkaloids Selmi named 

 ptomaines. Brieger, finding the bases derived from the products of 

 putrefaction less poisonous than those obtained from the pathogenic 

 bacteria, suggested the' term toaains for the latter. Ptomaines have 

 been divided into two classes — those which are non-oxygenous, liquid, 

 and volatile, and those which are oxygenous, solid, and crystallisable. 

 They are, for the most part, precipitated by the ordinary reagents 



39 



