THE TISSUES 31 



affinity for the interstitial substance, and which thus forms 

 a series of black lines between the cells. 



(B) Fat Cells. In the areolar tissue of many parts of the 

 body fat makes its appearance in the cells round the smaller 

 blood vessels, and when these cells occur in masses Adipose 

 Tissue is produced. 



Little droplets of oil first appear, and these become larger, 

 run together, and finally form a large single globule, distend- 

 ing the cell, and pushing to the sides the protoplasm and 

 nucleus as a sort of capsule (Fig. 10). 



FIG. 10. Fat Cells stained with osmic acid, and lying alongside 

 a small blood vessel. 



If the animal be starved, the fat gradually disappears out 



of the cell, and in its place is left a clear albuminous fluid 



which also disappears, and the cell resumes its former shape. 



The fats are ether derivatives usually of the triatomic 



alcohol glycerin 



(OH 



C 3 H 5 OH 

 (OH 



by the replacement of the hydrogen of the hydroxyl molecules 

 by the radicles of the fatty acids. 



The most abundant fatty acids of the body are : 



Palmitic Acid, C 16 H 31 O,OH 



Stearic Acid, C 18 H 35 0,OH 



Oleic Acid, C 18 H 33 0,OH 



