VTTAMINES AND GROWTH OP STREPTOCOCCUS 



461 



in the tables. In makinp; the dihitions of 0.02 per cent and 0.002 

 per cent of the fats and oils the following methods were used: 

 To dilution blanks containing 100 cc. of 1 per cent peptone, 

 1 cc.of the oil was added and an emulsion obtained by thorough 

 shaking. By adding 1 cc. and 0.1 cc. to our media we obtained 

 the percentages of fat mentioned above. The main point to 

 be observed however is that even down to 0.002 per cent of oil 

 in the medium there was a stimulation of growth. This small 



TABLE 4 

 Effect of small amounts of butterfat, rape and mineral oils on the growth of a 



streptococcus 



Butter 1 per cent. 



Butterfat 1 per cent. 



Bacteria per cc. 



f first experiment 430, 000 



■\second experiment in 1 : 10, 000 dilution 



ffirst experiment 11, 000, 000 



'\second experiment 14,000,000 



amount of oil could hardly be distinguished on the surface of 

 the media even on careful examination. At the same time other 

 media were made in which the oils butterfat, rape and mineral 

 or extracts from them, were added, in the following way: 100 

 cc. of water was shaken up with 5 cc. of the fat and oils for a 

 period of three hours. The bottles were than set aside in the 

 laboratory for several days after which time was a layer of oil 

 at the surface of the water but the water itself was slightly cloudy. 

 Two cubic centimeters of this emulsion, if it was an emulsion, 

 since we dealt with pure oil and distilled water, were added to 



