Studies in Fat Metabolism of Timothy Grass Bacillus. 275 



bably due to a small amount of carbohydrate carried over from the potato 

 slopes (see below). 



0-75 



0-50 



0Z5 



Days o 



grams of 

 acetic add- 

 per /oo.c-c 

 of medium. 



JO 15 



Curve 3. 



20 



Z5 



Since it has been shown in earlier experiments that no acetic acid accumu- 

 lates during the growth of the organism on glucose, and since acetic acid 

 has been shown by many workers to be a frequent intermediate product in 

 the breakdown of glucose by bacteria, it seemed worth while to ascertain 

 whether the presence of other substances might not confer on the Timothy 

 grass bacillus the power of utilising this compound. 



Experiment 5. — Utilisation of Acetic Acid in the presence of Lactic Acid 



or of Glucose. 



Sixteen Koux bottles, containing the usual inorganic medium with 1 per 

 cent, lactic acid (added in the form of calcium lactate) and - 5 per cent, 

 acetic acid (added as sodium acetate), were treated as described in Experi- 

 ment 1. Acetic acid was estimated on 20 c.c. of the diluted medium. It 

 was found that a correction had to be introduced owing to a small constant 

 amount of lactic acid distilling over with the acetic acid. The amount of 

 the correction was ascertained as follows : — 20 c.c. of diluted medium, con- 

 taining 1*2 per cent, of lactic acid only, were distilled exactly as described 

 above for acetic acid. A second distillation of 20 c.c. of the medium, con- 

 taining 1*2 per cent, lactic acid and 5 per cent, acetic acid was carried out 

 under exactly the same conditions. The number of cubic centimetres of 

 - lN baryta neutralised by the lactic acid distilled over in the first experiment 

 was then deducted from the number of cubic centimetres of baryta neutral- 

 ised by the lactic and acetic acids distilled over in the second experiment. 

 The difference gave the number of cubic centimetres of baryta neutralised by 

 the acetic acid only. It was found that the amount of lactic acid distilled 

 over under the standard conditions was fairly constant (corresponding to 



