CONNECTIVE TISSUES 



41 



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 to form a sort of capsule (fig. 11). 



Fig. 11. — 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. 



Fats. — The ordinary fats are esters of the triatomic 

 alcohol, glycerol (see Appendix) — 



OH 



CsHs^ OH 



i 



(oh 



formed by the replacement of the hydrogen of the hydroxyls 

 by the radicles of the fiitty acids. 



