THE EFFECTS OF BACTERIA. 121 



subtilis 1.7 c.c., bacillus anthracis 0.9 c.c. ; bacte- 

 rium vulgare was the only one which did not produce 

 liquefaction. 



4. In fluid, non-albuminous, glycerin-containing 

 (free from sugar) nutrient media, very few bacteria 

 produce proteoly tic ferments for example, bacterium 

 prodigiosum and bacterium pyocyaneum. The pro- 

 duction of ferment also appears to be less on pep- 

 tone bouillon than on peptone - bouillon gelatin 

 (Fermi). 



Upon albuminous nutrient media the liquefying 

 bacteria produce bitter products of disassimilation 

 for example, this is done in milk by very many 

 varieties (Hiippe) An enumeration of the trypsin- 

 forming varieties is unnecessary because they are 

 characterized as trypsin-producers by their liquefac- 

 tion of gelatin. 



The other ferments have been studied less care- 

 fully. 



Diastatic ferments convert starch into sugar. They 

 are demonstrated in the following manner; A thin 

 starch paste containing one per cent thymol is com- 

 bined with a culture to which one to two per cent thy- 

 mol has been added, and is kept six to eight hours in 

 the incubating chamber. A little Fehling's solution is 

 then added and sugar is recognized by the reduction 

 of copper (reddish-yellow precipitate) on boiling. 

 We can also make a direct examination of mashed 

 potato cultures of the bacteria by boiling the cultures 

 and testing the extract. 



According to Fermi about one-third of the varie- 

 ties examined only upon albuminous nutrient media 

 possess the power of forming such a ferment (A. H., 



