458 S. HENRY AYERS AND COXJRTLAND S. MUDGE 



EXPERIMENTS WITH FATS AND OILS 



We became interested in the effect of fats and oils as sources 

 of growth promoting substances from the results obtained by 

 Dr. Sherman of these laboratories, \Yho found that fat-soluble 

 A was apparently necessary for the growth of some of the organ- 

 isms of the high acid group. 



In all of our experiments the following basic medium was used: 



Peptone (Dif co) 10 grams 



Autolized yeast 10 grams 



Distilled water 1,000 cc. 



pH 7.4 



Fifty cubic centimeters of this medium were placed in 100 cc. 

 Erlenmeyer flasks and 0.5 cc. of the fat or oil to be studied was 

 added before sterilization at 15 pounds for thirty minutes. This 

 gave a concentration of 1 per cent of the oil in the medium. In 

 the first experiments butter-fat and cod-liver oil were used. The 

 butterfat was prepared from sweet cream churned into butter 

 and washed with warm water several times. As a final process 

 the fat was filtered through paper into a clean, dry beaker in 

 which it was stored at about 5°C. during the course of these 

 experiments. Using the same culture of streptococcus employed 

 in the experiments with water-soluble B it was found that both 

 butterfat and cod-liver oil stimulated the growth considerably 

 during the first twenty-four hours. These experiments were 

 repeated several times and the same results were obtained. 

 WhUe these results indicated that fat-soluble A might be respon- 

 sible for the stimulation it was decided to try ohve oil which is 

 beUeved not to contain this vitamine. The same stimulation 

 occurred however as with butterfat and cod-Uver oil. This 

 seemed to present evidence that fat-soluble A was not responsible 

 for the stimulation. 



While it is generally considered that oUve oil does not contain 

 fat-soluble A, the work of Drummond and Coward (1920) 

 indicates that it may be present in small amounts. For this 

 reason it was decided to use oil which could hardly be suspected 

 of containing fat-soluble A and white mineral oil was therefore 



