210 THE INCOME OF ENERGY 



glass 2. Again shake and pipette as before, and 

 repeat this process ever) 7 three or four minutes 

 until the experiment is completed. The begin- 

 ning of the experiment and the time of each 

 pipetting must be carefully noted. If the pipet- 

 tings are three minutes apart, then the first drop 

 of oil will have been exposed three minutes to 

 the action of the pancreatic juice, the second 

 drop six minutes, the third nine minutes, and 

 so on. 1 



The gradual increase in fatty acid will be 

 shown by the gradual increase in the amount 

 of the spontaneous emulsion. 2 



It has just been shown that lipase will hydro- 

 lyze neutral fats into fatty acid and glycerine. 

 We must now enquire whether this ferment 

 ean effect the synthesis of fats, in other words 

 whether its action is reversible. For this pur- 



1 Each ford : Journal of physiology, 1891, xii, p. 81. Rach- 

 ford used J c.c. fresh pancreatic juice obtained by placing a 

 glass tube in the pancreatic duct of the rabbit (see page 80). 



2 " There is a possible error in this method which had better 

 be spoken of here. It would seem that the alkali of the pan- 

 creatic juice would combine with the fatty acids forming soap, 

 and in this way the oil would soon be emulsified in the juice 

 itself and not separate after shaking. This would indeed be a 

 serious drawback if it actually occurred, but in truth it does not 

 occur until late in the experiment after we have obtained the 

 information we have sought by the spontaneous emulsion 

 method." (Eachford, loc. cit., p. 82). 



