PHYSIOLOGY 



37 



synthesized, but, on diluting with water, the fat is spHt up 

 again. This same author * has pubhshed important observa- 

 tions on the synthesis of fats in oily seeds mainly from the 

 carbohydrates glucose, sucrose, and starch. These substances 

 are synthesized in the order given, the last two being first 

 hydrolysed. The initial acids to be formed are characterized 

 by a low iodine value, showing that they are saturated. 

 Further, since the Reichert Meissl value is constant and 

 does not vary with the acid number, it is concluded that the 

 acids first formed belong to the higher members of the fatty 

 series. The saturated acids are followed by the unsaturated. 

 Ivanow gives the following scheme to indicate the essential 

 stages in the synthesis of fat in a typical instance such as the 

 seed of flax : — 



/Glycerol \ 



Carbohydrates 



>Fat. 



^Saturated- 

 fatty acid. 



■Unsaturated- 

 fatty acid. 



The iodine value of a fat is not necessarily constant, as is 

 shown by the observations of Eyre "j* who found that this value 

 steadily increased during the formation of the seed of the flax. 



The extracts of young seed have a high content of free fatty 

 acid, which rapidly decreases as the seeds develop. This in- 

 dicates that the glycerol appears later than the fatty acid, or 

 else the combination of the glycerol and fatty acid is impeded 

 by some factor. 



After the fourteenth day there is a rapid and more or less 



* Ivanow : " Beih. bot. Centr.," 1912. 28, 159. 



t Quoted by Armstrong and Allen ; " J. Soc. Chem. Ind.," 1924, 43, 

 207 T. 



