188 Prof. H. E. Armstrong and Mr. H. W. Gosney. 



But in view of our observation that under 40 per cent, of fatty acid is 

 convertible into fat, even when no water is present, it is difficult to under- 

 stand how the fatty acids are completely reconverted unless there be some 

 mechanism whereby the fat is separated from the fatty acid as it is formed — 

 or some means by which the acid is held in abeyance until it is required. 

 May it not be that the clue is afforded by the observations above referred to 

 with reference to the presence of fat in the tissues in a cryptic form ? Lipase 

 apparently is a " carboxylase " which has the power of determining the 

 hydrolysis of the ethereal salts of all the very weak carboxylic acids and, 

 within limits, is more effective the less soluble the acid and the alcohol from 

 which the salt is derived ; presumably, the argument applies equally to the 

 synthetic activity of the enzyme. It is therefore probable that, under the 

 influence of lipase, fatty acid may become associated with hydroxylic centres 

 in the protoplasmic complex and that such withdrawal may be the cause of 

 its cryptic existence in muscular tissue. 



The effect on health of an absence of fat from the diet, to which Arctic 

 travellers have called attention, is noteworthy from this point of view. 

 Stef ansson, in his recent book ' My Life with the Eskimo,' * states that the 

 symptoms that result from a diet of lean meat are practically those of 

 starvation ; during the winter period, even when gorged with caribou meat 

 free from fat, he and his party felt continually hungry ; the clogs, though they 

 got more meat than dogs usually get, were nothing but skin and bones. 

 Previously, when they had lived practically on oil alone, taking a teacupful 

 of oil a day, there were no symptoms of hunger ; they grew each day sleepier 

 and more slovenly, he says, but at the end of their meal of long-haired caribou 

 skin (to give bulk) and oil felt satisfied and at ease. 



On the assumption that fat is not always laid down as such but frequently 

 reconstructed in situ, the presence of glycerol in the necessary amount at the 

 seats of synthesis has to be accounted for. Owing to the solubility of this 

 substance, it cannot well be supposed that, when fat is hydrolysed, the fatty 

 acid and glycerol always remain together in the required proportions : it is 

 more probable that the glycerol becomes separated from the acid to a greater 

 or less extent and that the deficit is derived from carbohydrate : it is on this 

 account, at least in part, perhaps, that it is desirable that a certain minimum 

 ratio should be preserved between fat and carbohydrate in our food. 



We are indebted to the Hull Oil Manufacturing Company, Ltd., for having 

 placed at our disposal Indian castor seed of recent growth for the purpose of 

 this inquiry. 



* Macmillan and Co., London, 1913, pp. 140-141. 



