The "Bachman Test." 



53 



Experiment i. To test the applicability of the method to "B 

 as prepared by McCollum 1 from Navy Bean. 



Vitamine extract 



Contents of Tubes. 



Per Cent, of Gas-formation by Days. 



1. Control tube. Contained Nageli solution 

 and one loopful of yeast cell suspension . . 



2. Control tube 2. Contained Nageli solu- 

 tion, loopful yeast cell suspension and 1 

 c.c. of a dextrin solution made by dis- 

 solving 20 gms. dextrine in 150 c.c. of dis- 

 tilled water. The dextrin solution was 

 sterilized in the Arnold machine at ioo° C. 



3. Control tube 3. Contents same as tube 2 

 but the dextrin solution was sterilized 

 again, after Arnold treatment, for 20 

 minutes in the autoclave at 15 lbs. and 

 about 120 0 C 



4. Tube contained Nageli, loop of yeast and 

 1 c.c. of a dextrine vitamine extract from 

 Navy Bean (for preparation see explana- 

 tion below) sterilized in the Arnold at 

 ioo° C 



5. Same as tube 4 but sterilized in the auto- 

 clave in addition to Arnold sterilization . . 



upset at this point 



40 



38 



37 



33 



Explanation: The vitamine dextrine solutions were obtained by first extracting 

 86 gms. of Navy bean flour with ether in the Soxhlet for 18 hours. The residue was 

 then extracted for two six hour periods with boiling alcohol (95 per cent.) in a reflux 

 condenser. The alcohol extract was mixed with 20 gms. of dextrine and evaporated 

 to dryness. The solution was made by dissolving this dextrin vitamine in 150 c.c. of 

 distilled water. The control dextrin solution was made by dissolving 20 gms. of 

 dextrine in 150 c.c. distilled water. All the solutions were subjected to two 30 

 minute periods in the Arnold sterilizer with a 24-hour incubation period intervening. 

 The materials tested in tubes 3 and 5 were then given an additional 20 minutes in 

 the autoclave at 15 lbs. and approximately 120 0 C. A pure culture of the Fleisch- 

 man round yeast was used. The suspension was made by transferring to 5 c.c. of 

 sterile water several loopfuls of the agar slant culture and the tubes were inoculated 

 with one loopful of this suspension. Our tubes were incubated at 32 0 C. The CO2 

 is very rapidly reabsorbed by the Nageli solution and sealing the tube with mineral 

 oil was not effective. Consequently readings may be discontinued after the per 

 cent, of gas reaches the maximum. 



1 "A Study of the Dietary Essential, Water-soluble B.," by E. V. McCollum, 

 Journ. of Biological Chemistry, XXXIII, 55. 



