166 SECTIONAL ADDRESSES. 



reactions which one expects to find in syntheses in the cell and involves 

 only the loss of water and carbon dioxide. 



(1) CH3 • CHOH • COOH -> CH3 • CO • COOH+Hj 



(2) CHs • CO • COOH ->- CH., • CHO+CO.2 

 (3)2CH3CHO -> CHs-CHtCH-CHO+HaO 



(4) CH3 • CH : CH • CHO+ Ha -> CH3 • CH2 • CH.j • CHO 



(5) CH3 • CH2 • CH2 • CHO+ -^ CHs • CH2 • CH2 ■ COOH. 



Repetition of reactions (3) and (4) would produce aldehydes corres- 

 ponding to the higher fatty acids, and only one atom of oxygen is required 

 for the final oxidation of the aldehyde. All the hydrogen required for the 

 reduction of the unsaturated aldehydes would be supplied by the dehydro- 

 genation of lactic to pyruvic acid. But even if these reactions turn out 

 to be the right ones the problems still remain as to how they are accurately 

 controlled within the cell. Some of the substances concerned in them are 

 difiusible and very reactive, and we should have to explain how diffusion 

 away from the site of reaction is prevented. To overcome difiicidties of 

 this kind it is becoming common to invoke the intervention of surface 

 forces. There is, however, not much experimental evidence as yet which 

 helps us to explain by such intervention the mechanism of synthetic pro- 

 cesses even of such a simple kind as the reversal of an enzyme action. 



Freundlich in his Liversidge Lecture to the Chemical Society last year 

 described experiments on the influence of charcoal in modifying the velocity 

 of certain reactions. Bromoethylamine is converted by caustic soda into 

 dimethyleneimine. The amine is more strongly adsorbed than the imine 

 and therefore the conversion should be slower in the presence of charcoal 

 than in homogeneous solution. Experiment verifies this. Further, di- 

 methyleneimine is converted into bromoethylamine hydrobromide iia 

 presence of hydrobromic acid. Because the bromoethylamine hydro- 

 bromide is more strongly adsorbed than the dimethyleneimine the conver- 

 sion should be more rapid in the presence of charcoal than in homogeneous 

 solution. This also was shown to be true. In addition it was demon- 

 strated that the change of the amine into the imine in neutral solution 

 stops earlier when charcoal is present than when it is absent. The equili- 

 brium obtained in homogeneous solution is thus disturbed in the sense that 

 the formation of capillary active substances {i.e. those more highly 

 adsorbed) is favoured. It follows from this that the stability of a substance 

 on a surface may be greater than in homogeneous solution under similar 

 conditions. It must be borne in mind, however, that in these experiments 

 very large quantities of charcoal were used compared with the amounts 

 of the substances whose equilibria were being studied. So much so that in 

 the reaction in alkaline solution the bromoethylamine was practically 

 completely adsorbed and the reaction was taking place entirely on the 

 charcoal surface. Can one postulate such conditions during the continuous 

 synthesis of substances in the cell, glycogen from glucose for example ? It 

 seems to me that to explain the rapid accumulation of synthetic products 

 such as fat or glycogen which we observe in cells something more than 

 a shift in the equilibrium of the reactions due to surface forces is neces- 

 sary. Such a condition favouring synthesis could only operate for a time 

 until the surface became saturated. We must therefore postulate some 



