CHAP. III.] AREOLAR TISSUE. 73 



the proper coat of the arteries, and it will be described with the 

 blood-vessels. 



In chemical constitution, this tissue differs remarkably from the 

 white fibrous tissue. It is unaffected by the weaker acids, or by 

 boiling, and will resist putrefaction, and preserve its elasticity 

 during a very long period. Very long boiling appears to extract 

 from it a minute quantity of a substance allied to gelatine; but 

 this is perhaps derived from the areolar tissue and vessels, which 

 always penetrate sparingly among its fibres, and cannot be sepa- 

 rated by dissection. 



There appear to be no vestiges of the nuclei of cells in this 

 tissue ; at least, we have failed to detect them. 



We have hitherto spoken of the two forms of fibrous tissue as 

 they occur in isolated masses ; but their distribution through the 

 body is far more extensive than this description would imply. In 

 a diffused form, blended with one another in very varying propor- 

 tions, and each one of them presenting a variety of modifications, 

 they compose the areolar tissue, which may now be conveniently 

 considered under a separate head. 



OF THE AREOLAR TISSUE. 

 (Cellular or Filamentous Tissue). 



This is very widely dispersed among the other tissues of the 

 body, and of itself constitutes a principal portion of some organs. 

 It serves the most important purposes in the construction of the 

 body, by binding together, and yet allowing movement between, 

 its elementary parts ; and it contributes largely to the formation 

 of membranes conferring protection by their toughness, resistance, 

 and elasticity. 



Microscopic Characters. When a fragment of the areolar tissue 

 from a favourable situation is examined, it presents an inextricable 

 interlacement of tortuous and wavy threads intersecting one another 

 in every possible direction. They are of two kinds. The first are 

 chiefly in the form of bands of very unequal thickness, and inelastic. 

 Numerous streaks are visible in them, not usually parallel with 

 the border, though taking a general longitudinal direction. These 

 streaks, like the bands themselves, have a wavy character, but 

 they are rendered straight by being stretched. The streaks seem 



