698 



METABOLISM 



yolk fat, some of it persisted in the blood for several hours. This in- 

 crease may have been owing to the flooding of the temporary storehouse 

 with fat, or, more probably, to a retarding influence that lecithin may 

 have on fat assimilation, for lecithin itself persists in the blood for a 

 long time after intravenous injection. 



During fasting, no increase in blood fat was found unless the animal, 

 by special feeding, had been stuffed with excess of fat prior to the fast- 

 ing period. The lipemia in this case indicates that fat is being trans- 

 ported from one place to another to serve as fuel for the starving tissues. 

 Narcotics were found to produce an increase in blood fat. Ether pro- 

 duced this increase during the narcosis, whereas morphine and chloro- 

 form did not do so until after recovery. The explanation given for the 

 ether effect is that a mixture of blood and ether has higher solvent power 

 for fat than blood alone. The explanation for the chloroform and mor- 

 phine effects is that a certain amount of breakdown of the tissue cells, 

 in which lipins are set free, supervenes upon the action of these narcotics. 



The blood fat also becomes enormously increased in about forty hours 

 after the administration of phlorhizin, and on the second or third day 

 after the administration of phosphorus. The special significance of 

 these facts we shall consider later in connection with the relationship of 

 the liver to fat metabolism. 



By comparison of the fatty acid, lecithin, and cholesterol contents of 

 blood during fat absorption, it has been found that there is a steady but 

 very variable increase in fatty acid, accompanied by no variation in 

 cholesterol, but with an increase in lecithin, which varies from 10 to -35 

 per cent, but does not run strictly parallel with the fatty-acid increase. 

 It is probable that this increase in lecithin represents that part of the 

 absorbed fat which is intended for immediate use in the tissues (page 

 705). The more or less independent increase in lecithin is of significance 

 in connection with the fact that in many pathologic conditions of so- 

 called lipemia the increase does not affect the fats of the blood but rather 

 the lipoids (i.e., lecithin and cholesterol). Separate analyses of blood 

 plasma and whole blood show the increase of lecithin to be much more 

 marked in the corpuscles than in the plasma, whereas the fatty-acid 

 increase is confined to the plasma. 



To illustrate some of these points the following table will be of value. 

 In it is shown the average distribution of fatty acid, lecithin and choles- 

 terol in normal individuals and in cases of diabetes, in which disease, 

 as has been known for long, there is marked disturbance of fat metab- 

 olism. 



