456 S. HENRY AYERS AND COURTLAND S. MUDGE 



similar manner. These results showed quite plainly that the 

 cabbage extract contained some growth promoting substance, 

 but the increase in acidity with the increase in percentage of 

 cabbage extract also indicated that there was sugar present. 

 This fact led us to consider the effect of sugar as a growth promot- 

 ing substance. An analysis of the cabbage extract for which we 

 are indebted to Doctor Rupp of these laboratories, showed that it 

 contained 1.4 per cent of reducing sugar. Calculations showed 

 that when the cabbage extract was incorporated with the peptone 

 solutions the resulting media contained 0.014, 0.07 and 0.7 per 

 cent of sugar for the 1, 5, and 50 per cent cabbage media, respec- 

 tively. In order to show the effect of these percentages of sugar 

 on the growth of the streptococcus a series of media was prepared 

 as previously described except that a 1.4 per cent glucose solution 

 was incorporated in the media instead of the cabbage extract. 

 The growth in these last media was compared with that in the 

 cabbage extract media mentioned. 



From the results of this comparison, shown in table 2, it will 

 be seen that growth in peptone media with cabbage extract was 

 practically identical with that in the peptone media ■nith the 

 glucose solution. The growth increased, generally speaking, 

 with the increase in the percentage of cabbage extract, and, in 

 a similar manner, with the increase in the percentage of glucose 

 solution. It shovdd be remembered that the glucose solution 

 contained 1.4 per cent reducing sugar so as to correspond ■with 

 the cabbage extract. It is particularly interesting to note the 

 increase in growth due to the incorporation of only 1 per cent of 

 the glucose solution which gave a sugar content in the medium of 

 only 0.014 per cent. From these results it seems evident that a 

 very small amount of sugar acts as a growth-promoting substance 

 for some of the streptococci. 



We wish to emphasize that Avhen extracts of plant tissues are 

 used as a source of growth-promoting substances, the possible 

 effect of sugar and other reducing substances present must be 

 given considerable thought before the growth promotion can be 

 attributed to vitamines. This is not only true when plant tissues 

 are used but holds equally well for any extracts which may contain 

 sugars. 



