SECTION III 

 THE HISTORY OF FAT IN THE BODY 



FAT is found in the body in various situations. In a fat animal the largest 

 amount occurs in the panniculus adiposus in the subcutaneous tissues. 

 Large quantities are also found surrounding the abdominal organs and 

 between the layers of the mesentery and great omentum. In this adipose 

 tissue the fat is enclosed within and distends connective-tissue cells, the 

 protoplasm of which is reduced to a thin pellicle round the fat globule. 

 Fat is also found in the form of granules in more highly specialised cells, 

 such as the secreting cells of the liver or the muscle-cells. The condition 

 of these cells is often spoken of as fatty infiltration, or fatty degeneration, 

 according to the circumstances which are responsible for bringing about 

 the deposition of fat. We shall have to discuss later on how far we are 

 justified in assuming any real distinction between these two processes. 

 From the physiological standpoint the most important intracellular depot 

 of fat is in the liver. If this organ be deprived of glycogen and fat by 

 starvation, a fatty meal gives rise to a great deposition of fat in its cells. 

 There is apparently an antagonism between the processes which lead on 

 the one hand to the deposition of glycogen and on the other to the deposition 

 of fat. Thus an excessive carbohydrate diet, which induces great deposition 

 of fat in the subcutaneous tissues, only causes the formation of glycogen 

 in the liver. The glycogen must be got rid of before it is possible to cause 

 the deposition of fat. On this account, the normal content in fat of the 

 livers of different animals varies with their ordinary diet. Fishes, e.g. the 

 cod, which take but little carbohydrate in their food, have generally a very 

 large quantity of fat in their livers. Herbivorous animals, as a rule, have 

 practically no fat in the liver. 



Fat also occurs in certain secretions, e.g. the milk and the sebum, its 

 function in the latter case being mainly protective. 



Besides the visible deposit of fat found in adipose tissue and in other 

 situations a large amount of fat is always present built up into the proto- 

 plasm of the cells in such a condition that its presence cannot be detected 

 by histological means. The presence or absence of visible fatty globules 

 affords very little clue to the total quantity of fat in the cells. Thus in one 

 case the heart muscle, which had undergone extreme 'fatty degeneration 

 and was loaded with fat globules, contained 19 per cent, of its dried weight 

 of fat. A heart muscle taken from a normal animal at the same time, 

 presenting no visible fat globules, contained 17 per cent, of fat. 



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