New Method for Detection of Liquefying Bacteria. 169 



anti-ferment suggested to the writer that this apparatus might be 

 of service for the early detection of the liquefying propensities of 

 those bacteria, which under the methods commonly employed, 

 may not reveal this function for one to four weeks. The identifica- 

 tion of Bacillus coli in the bacteriological examination of water 

 requires several tests, all of which may be completed within four 

 days, with the exception of that for the action of the bacillus in 

 question on gelatin which calls for a fourteen-day incubation at 

 20 0 C. It is generally agreed, among sanitarians, that a shortening 

 of the period of this test is highly desirable, but, although a number 

 of expedients have been suggested, none have been found suf- 

 ficiently simple and reliable to warrant adoption. 



Two special advantages pertain to the use of the viscosimeter 

 in the study of bacterial digestion of gelatin. First, it permits 

 incubation of the cultures at the most favorable temperature, 

 whether it may be 37 0 C, or higher, thus obtaining rapid growth 

 and enzyme production, although it should be added that these 

 activities are not always correlated; and second, it enables one 

 to detect very slight reductions in the viscosity of the medium, 

 in fact long before any visual change is apparent. It has been 

 found, that, although the majority of cultures, growing well at 

 37 0 C, and showing the first evidence of liquefaction at room 

 temperature within three to ten days, may be detected by this 

 method within twenty-four hours, it is best to make the examina- 

 tion after forty-eight hours. After this incubation practically all 

 of the actively growing cultures, which required up to fourteen 

 days for the production of the first visual traces of liquefying 

 activity at 20 0 C, had produced sufficient change in the viscosity 

 to permit detection. For the still slower liquefiers, those ordi- 

 narily requiring a three to four weeks test at 20 0 C, and for the 

 cultures which grow sluggishly, an incubation of four to six days 

 is necessary for the unquestioned revelation of their fluidifying 

 propensities. 



The details in regard to the methods employed and the results 

 obtained will be given elsewhere. Briefly, fifteen per cent, nu- 

 trient peptone gelatin, tubed in 4 cubic centimeter amounts, was 

 seeded with a definite dosage of twenty-four-hour agar growth of 

 the culture, emulsified in salt solution. These seeded tubes to- 



