THE CONNECTIVE TISSUES. 



[OH. IV. 



they are made of condensed ground substance, not of cells, and 

 in other cases again (as in the cornea) they are of elastic nature. 





Jelly-like Connective Tissue. 



We have now considered connective tissues in which fibres of 

 one or the other kind predominate, and some in which the cells 



are in preponderance. We 

 come lastly to a form of 

 connective tissue in which 

 the ground substance is 

 in excess of the other 

 histological elements. This 

 is called jelly-like connec- 

 tive tissue. The cells and 

 fibres scattered through it 

 are few and far between. 

 It is found largely in the 

 embryo, notably in the 

 Whartonian jelly, which 

 surrounds and protects the 

 blood-vessels of the um- 

 bilical cord. In the adult 

 it is found in the vitreous 

 humour of the eye. 



Various points in the structure of the tissue are illustrated in 



figs- 5 8 (P- 43) and 73- 



The occurrence of large quantities of ground substances in 

 such tissues has enabled physiologists to examine its chemical 

 nature. Its chief constituents are water, and one or more 

 varieties of mucin, with traces of proteid and mineral salts. 



The foregoing tissues are sometimes called the connective tissues proper. 

 The remaining members of the connective-tissue group we shall reserve for 

 the next chapter. 



Fig. 73. Tissue of the jelly of "Wharton from 

 umbilical cord, a, connective-tissue cor- 

 puscles ; 6, fasciculi of connective-tissue 

 fibres; c, spherical cells. (Frey.) 



