STRUCTURAL CHARACTERS OF ANIMAL ORGANISMS. 49 



In some parts of the body, however, a different kind of inter- 

 cellular substance is formed, which is highly elastic, does not give 

 gelatine on boiling, and is not affected by weak acids or alkalies. 

 This is spoken of as Yellow elastic tissue. It is sometimes found 

 alone forming an elastic band or ligament, but more commonly 

 mingled with fibrillar tissue to form the common connecting 

 medium which lies under the skin and between the various other 

 textures. 



In Cartilage the intercellular substance secreted by the cells 

 is hard, and forms in the earlier stages of its development cases or 

 cell walls for the cells. These cases subsequently increase in thick - 



FIG. 29. 



A teased preparation of connective tissue, showing fine and coarse elastic 

 fibres mingled with bundles of fibrillar tissue and connective tissue corpus- 

 cles. 



ness, and become fused together into a homogeneous intercellular 

 substance, where ultimately the capsules belonging to the different 

 cells can no longer be distinguished from one another, so that in 

 the adult tissue there is seen to be a tough matrix of intercellular 

 substance, in which the cells are scattered, apparently occupying 

 small cavities. These cells, which are the remote offspring of 

 those which formed the tissue permanently, preside over its nu- 

 trition. 



