56 



Scientific Proceedings (51). 



days. Ten cubic centimeters were then tested for creatinine by 

 Weyl's method (adding several c.c. of a 10 per cent. NaOH solu- 

 tion and several drops of a freshly prepared sodium nitroprusside 

 solution, a positive reaction being indicated by the immediate 

 appearance of a dark red zone which soon turns to a greenish 

 color) and 50 c.c. were tested by the Folin method (adding 7.5 c.c. 

 saturated picric acid solution and 2.5 c.c. sodium hydrate, a 

 positive reaction being indicated by the production of an orange- 

 red color similar to the color produced by a potassium bichromate 

 solution). As controls, a strain of each of B. coli communis, B. 

 proteus, V. cholerce asiatica, M. aureus, M. albus, and V. Metchni- 

 kovii were examined at the same time. A sterile peptone solution 

 itself gives with the Folin method a slight color which to a certain 

 extent interferes with the test; this, however, can be eliminated 

 by comparing the solution to be tested with the control. In only 

 one case, that of B. proteus, was the Folin reaction decidedly 

 positive, while V. cholerce asiatica, and several others gave a some- 

 what doubtful positive result. With the Weyl reaction a much 

 more accurate determination of the presence of creatinine can be 

 made. 



As regards the Mucosus capsulatus group, we found that 

 creatinine production is no criterion in differentiating the species, 

 since nearly all the strains gave negative reactions. That the 

 amount of creatinine which is produced as a result of bacterial 

 metabolism is very small is indicated in the results obtained by 

 the Folin method. That certain bacteria produce creatinine more 

 readily and in larger amounts than others is shown by the more 

 strongly positive reactions given by B. proteus. German's results 

 tend to show the same thing. His inability to get a positive 

 creatinine reaction with certain organisms in twenty-four hours, 

 which after a longer period of time gave positive reactions, does 

 not show that no creatinine was produced during the first twenty- 

 four hours, but rather that the amounts produced were so small 

 that the test appeared to be negative. That there are certain 

 bacteria which either do not produce any creatinine when grown 

 on a peptone medium or produce amounts of creatinine so small 

 that the Weyl reaction appears negative is shown both by Ger- 

 man's and our results. 



