THE CONNECTIVE SUBSTANCE GROUP. 



63 



lia ; 4, fat tissue ; 5, fibrous tissue proper ; 6, corneal tissue ; 

 7, iniejmuscular tissue ; 8, tendon tissue ; 9, elastic tissue ; 

 10, bone ; 11, cartilage ; 12, enamel ; and 13, dentine. The 

 word connective tissue\v&s first proposed by Johannes Mueller, 

 and is" sometimes used as synonymous with connective sub- 

 stance, but erroneously. The former is merely a variety of the 

 latter, and is usually intended to indicate one or other of the 

 flexible connective substances that form the interstitial material 

 of the body, and in that sense we shall use it for convenience 

 sake, but without implying any special histological character. 



In precise histological descriptions it is always best to use 

 the special name of the variety intended, such as mucous tis- 

 sue, adenoid tissue, and the like, where the structure happens 

 to be known. 



It is also well to state here that the term "cellular" tissue, 

 found in many of our anatomies, is apt to mislead the student. 

 The word "cellular" has no reference to cells, i.e., corpuscles, 

 but to the large cavities or spaces that exist in all loose connec- 



Fio 23. Gelatinous or mucous tissue. Human umbilical cord. 



tive tissues, of which the subcutaneous is an example. These 

 spaces are easily seen by the naked eye, when inflated with air. 



Mucous or gelatinous tis site. This is the most simple 

 form that is met with. It is seen to great advantage in the 

 embryonic umbilical cord, which also contains several other 

 varieties of connective tissue. 



The following method has been found best suited to demon- 

 strate it. Take a small piece of cord at about the third month 

 and immerse it a few weeks in Mueller's fluid ; make a thin sec- 

 tion through the very soft gelatinous part, then soak it a few 

 minutes in distilled water, to which subsequently a few drops 



