38 PKIMARY TISSUES : AEEOLAR TISSUE. 



not acted on by acetic acid. It is but little prone to decom- 

 position, and will exhibit its peculiar elasticity long after it 

 has been separated from the body, provided it be kept moist. 

 These two forms of tissue exist separately in certain parts 

 of the fabric, but they are much more frequently combined ; 

 and the proportion of the yellow elastic tissue which exists in 

 any such combination, may be readily determined under the 

 microscope by the use of acetic acid, which renders all the 

 white fibrous structure so transparent, that the yellow fibres 

 are seen completely isolated in the midst of it. 



24. One of the tissues which is composed of such an 

 admixture of white and yellow (or non-elastic and elastic) 

 fibres, is the one which was formerly called "cellular," but 

 which is now more correctly designated as Areolar. 1 This 

 is composed of a mesh-work of fibres, and of bands of fibrous 

 membrane, which are interwoven in such a manner as to leave 

 very numerous interstices and cavities amongst them, having 

 a tolerably free communication with each other (fig. 3). These 



Fig. 3. PORTION OP AREOLAR TISSUE. 



cavities are filled during life with a serous fluid ; 2 and it is a 

 necessary result of the communication between them, that if 

 an accumulation of this fluid takes place to an undue extent, 



1 From the Latin areola, a small open space. 



2 A fluid resembling the serum of the blood, diluted with water 

 ( 236). 



