304 HUMAN PHYSIOLOGY 



in the diet. So an animal eating a vegetable oil does 

 not store the same oil in its adipose tissue, but accumu- 

 lates there a fat which conforms to its own standard. 

 The only exception is noted when a fast is followed by 

 abundant feeding; at such a time there may be some 

 retention, for a while, of a distinctly foreign fat. 



Most of the fat in the body is in what we have called 

 adipose tissue. When we spoke of peptic digestion we 

 described this as a tissue rich in fat but not composed 

 solely of that material. It is a form of connective tissue 

 with fibers between the cells. But while, as a rule, the 

 intercellular substance makes up the bulk of any con- 



FIG. 64. Cells in adipose tissue distended with fat. Note the 

 capillary, fibers, and undeveloped cells. 



nective tissue we recognize an exception in this case. 

 The fat carried is intracellular, that is to say, enclosed in 

 the cells instead of being placed between them. It is so 

 abundant that the cells have a swollen appearance, their 

 nuclei are pushed to the surface, and their true proto- 

 plasm is a mere envelope for the fat drops within. 



Adipose tissue is found even in lean animals to an 

 amount not usually suspected. A considerable mass is 

 normally present below the diaphragm and about the 

 kidneys. The white marrow in the hollow shafts of the 

 long bones is essentially adipose tissue. When the 



