124 BIOLOGY OF PNEUMOCOCCUS 



nature was the urine test of Dochez and Avery, 821 who had ob- 

 served that in vivo as well as in vitro, Pneumococcus produced a 

 soluble specific substance, and that with an appropriate immune 

 serum its presence could easily be detected. Type III organisms 

 formed the largest amount of the substance, Type II somewhat 

 less and Type I the least. The majority of patients who failed to 

 show the precipitable substance in the urine recovered, whereas the 

 mortality was high among cases in which its presence was demon- 

 strable. A positive test was also of diagnostic significance. 



SPUTUM PRECIPITINOGEN 



A rapid method depending upon the demonstration of pneumo- 

 coccal precipitinogen was that of Mitchell and Muns (1917). 904 

 They ground sputum with fine sand to disrupt the cells and release 

 the soluble substance, extracted the mixture with salt solution, 

 centrifuged the extract until clear, and then added immune serum 

 to the supernatant fluid. The test required only an hour for its 

 completion and gave clear-cut results for Type I, II, and III 

 pneumococci. Those sputums which gave no reactions were classed 

 as Group IV. The success of the method depends on obtaining a 

 specimen rich in pneumococci. 



SPUTUM DIGESTION 



Krumwiede and Noble, 761 also responding to the demands of the 

 time, sought by digesting sputum with antiformin to bring the pre- 

 cipitinogen into solution, but difficulties were experienced in apply- 

 ing this technique to all specimens, and the final results were often 

 unsatisfactory. In a second paper, Krumwiede with Valentine, 762 

 abandoned the use of antiformin and, instead, coagulated the spu- 

 tum with heat. They broke up the coagulum and extracted the 

 soluble antigen with saline solution in a boiling water-bath, cleared 

 the extract by centrifugation, and then layered or floated the anti- 

 gen over the type serums. The authors incubated the tubes at 50° 



