VITAMINES AND GROWTH OF STREPTOCOCCUS 455 



a normal manner. The results of these experiments when in- 

 terpreted in hght of our present knowledge of water-soluble B, 

 and apjilied to the streptococcus studied, permit only the con- 

 clusion that this vitaminc is not the srowlh-promotinp; substance 

 of yeast extract. It is interesting to note that Funk and Dubin 

 (1921) working on the vitamine reciuircments of yeasts and 

 bacteria, have isolated a substance which they believe to be 

 definite and specific for the stimulation of the growth of yeast. 

 This substance, which was separated from vitamine B, they call 

 vitamine D, 



EXPERIMENTS WITH CABBAGE EXTRACTS 



It has been found that extracts from plant tissues apparently 

 contain growth promoting substances for microorganisms, and 

 cabbage seems to have given particularly good results. We tried 

 one experiment in order to determine whether or not cabbage ex- 

 tract was valuable for the growth promotion of the streptococcus. 

 One hundred cubic centimeters of finely minced cabbage were 

 added to 300 cc. of distilled water and allowed to stand for forty- 

 eight hours in the ice box. The suspension was then steamed 

 for thirty minutes and filtered. Fifty cubic centimeters of 2 per 

 cent Difco peptone solution were distributed into a series of 

 flasks. To these flasks were added increasing amounts of the 

 cabbage extract, these amounts being 1 cc, 5 cc, and 50 cc. 

 Whenever necessary the medium was made up to 100 cc. and dis- 

 pensed into tubes. Thus we had a series of media, one contain- 

 ing 1 per cent peptone alone and the other three having 1 per 

 cent, 5 per cent, and 50 per cent of cabbage extract. Series of 

 each of these media were inoculated with severail different cul- 

 tures (one of them being the culture used in the other experi- 

 ments), were incubated for twenty-four hours, and then examined 

 for growth and reaction. It was found that in the plain peptone 

 without cabbage extract there was a fair growth of some of the 

 streptococci, but with others the growth was questionable. In 

 all of the tubes containing cabbage extract, growth was observed 

 and the increase was more or less proportional to the increase in 

 percentage of cabbage extract. The acidity also increased in a 



