FATS 199 



The character of the depot fat is easily influenced by the 

 kind of fat in the diet. In dogs fed on mutton fat, for 

 instance, the depot fat approaches mutton fat in type. 

 This would seem to show that transformation of food fat 

 into a particular kind of body fat within the intestinal 

 wall does not normally take place to any appreci'able 

 extent, and that the character of the depot fat is an 

 average of that of the fats eaten ; there being normally 

 very little change of diet, the character of the depot fat 

 remains fairly uniform, 



2. The Tissue Fat. — By this is meant the fat which is 

 built up into the structure of the hving cell, and not that 

 which is found fiUing up the spaces in every tissue. The 

 latter is only a form of depot fat. Tissue fat differs from 

 depot fat in two respects. First, the fatty acids form 

 only 05 per cent, of the molecule, suggesting that they 

 are built up into a complex molecule, such as lecithin. 

 Secondly, it has a high iodine value, indicating a high 

 percentage of unsaturated fatty acids. The characteristics 

 of tissue fat do not varv with the diet. 



3. The Liver Fat. — -The liver contains a higher propor- 

 tion of fat than any other organ, in man as much as 

 70 per cent, of the dry substance being fatty acid. Under 

 ordinary conditions the liver fat resembles tissue fat in 

 having a high iodine value and a low percentage of fatty 

 acid ; the fat is therefore in the form of a lecithin. But 

 after the ingestion of a considerable amount of fat of low 

 iodine value, the liver fat assumes a low iodine value, 

 this change preceding the similar change which occurs in 

 the depot fat. Fat after absorption, therefore, is first 

 deposited in the Hver. 



In the condition known as fatty itifiltration there is a 

 deposit of fat in visible triglyceride form in the hepatic 

 cells. This occurs naturally during pregnancy and lacta- 

 tion, and pathologically in diabetes and after poisoning with 

 chloroform or phosphorus. The fat deposited comes not 

 from the complex hpoids of the liver but from the fat 



