94 Fermentation and Kindred Phenomena. 



organisms, and believes that two species are especially active, 

 at all events in the earlier stages of the process. These he 

 terms protens mirabilis and proteus vulgaris respectively. They 

 are remarkable for the variety of forms they can assume, and 

 furnish an excellent example of pleomorphism. Hauser has 

 illustrated his work on the subject with some very beautiful 

 micro-photographs (taken from nature) of these organisms in 

 their various stages of existence. 



Many interesting and highly important observations have 

 been made with regard to the nature of the substances produced 

 during putrefaction. Thus it has been shown by Selmi and 

 others that putrefying animal matter frequently contains certain 

 substances closely resembling in their properties some of the 

 most poisonous alkaloids found in the vegetable kingdom. 

 These have been called Ptomaines, and their significance is very 

 great when we consider that in certain cases of suspected poison- 

 ing, corpses are often exhumed and are examined for alkaloids 

 among other poisons. It is by no means impossible that a 

 ptomaine might be mistaken for a poisonous alkaloid, and thus 

 a false suspicion or even conviction arise as to the cause of 

 death. 



Again, many cases of poisoning have occurred from the con- 

 sumption of tainted meat, fish, cheese, &c. In such cases it is 

 also possible that the poisonous principles are ptomaines. It 

 has also been shown that " by the putrefaction of animal sub- 

 stances a body can be obtained — the septic poison or sepsine — 

 which is isolated by various chemical processes destructive of 

 every living organism, and which on injection into the vascular 

 system of animals, especally dogs, in sufficient quantities 

 occasions a marked febrile rise of temperature, and is capable 

 of causing death." * 



Organisms causing definite chemical changes. — It is conceiv- 

 able that every species of micro-organisms induces perfectly 

 definite chemical changes in the medium in which it thrives. 

 There are, however, certain species which induce very simple 

 chemical reactions, and many of the latter are every-day 



-* Klein. 



