38 
PRIMARY TISSUES :—AREOLAR 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} 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 of Areolar Tissue. 
cavities are filled during life with a serous fluid ; 1 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 ). 
