52 NORMAL HISTOLOGY. 



become more and more abundant, arranging them- 

 selves now in bundles, and again to form irregu- 

 lar networks. The cells approach more and more 

 closely to the type of the adult connective-tissue 

 cells as development goes on ; the intercellular sub- 

 stance loses its- soft gelatinoid character, and is 

 finally replaced by the fibrillated and elastic fibres 

 with which we are already familiar. 



The process of development is a very gradual 

 one, and although the younger forms of embryonal 

 connective tissue and the adult connective tissue 

 are distinct enough, we are yet unable to separate 

 them sharply, since they merge so gradually into 

 one another. In general, however, simply as a mat- 

 ter of convenience, we call connective tissue which 

 is almost entirely made up of spheroidal, spindle- 

 shaped, or flattened cells, in which little accumula- 

 tion and little differentiation of the 'intercellular 

 substance has occurred, embryonal tissue ; while to 

 that older form, which consists of variously shaped, 

 spheroidal, flat, branching, and anastomosing cells, 

 with a gelatinoid, homogeneous, or partially fibril- 

 lated intercellular substance, the term imicous tissue 

 is usually applied. The name mucous tissue was 

 given to this form of young tissue, because the soft 

 gelatinoid intercellular substance was found to con- 

 tain a certain amount of mucin, which may be 

 thrown down in the form of a whitish, often stringy 

 precipitate, by the addition of acetic acid. At 



