FIBROUS TISSUE. 



555 



more distinct. The first kind does not refract the light 

 strongly ; the second kind does, showing some chemical 

 difference in their composition. 



Cellular tissue, if dried, becomes a yellowish, brittle, 

 transparent mass ; but regains its former state if placed in 

 water. The fibres have a remarkable arrangement and 

 disposition. They are often deposited in a spiral manner ; 

 at other times they are regularly undulating. In fibres 

 taken from some parts of the body, we find a fasciculus 

 wound round in a spiral form. As a consequence, when 

 acetic acid is applied, we perceive projections of swollen 

 cellular tissue, and the depressions, from not having been 

 acted on, have a constricted appearance. The fibrous tissue 

 lining the eggshell, fig. 291, is the simplest form in which 

 it is found. 



Fat is generally found in the cellular tissue ; it is not 

 secreted from it, but is contained in its proper cells, and 

 termed adipose-tissue ; the elementary cells of which are 

 from the l-300th to the l-600th of an inch in diameter. 

 (Fig. 292.) The cell- wall is very delicate and transparent; 

 sometimes there are one or two nuclei enclosed. ^Ether 

 dissolves out the fat-cells from 

 the tissues. Acetic acid acts 

 upon the cell-wall, and causes 

 the contents to pass from within 

 outwards. 



Fibrous tissue, elastic and 

 non- elastic, is usually divided ; 

 into white and yellow fibrous 

 tissue. The yellow is elastic, 

 and of great strength, consist ing 

 of bundles of fibres which are 

 highly elastic, (Fig. 29 4, No. 2.) 

 The white (fig. 294, No. 1), 



though non-elastic, is Of great Fig. 292. Cellsfrom adipose tissue, or 

 Strength, and Of a Shining, /, magnified 100 diameters. 



silvery appearance. 



These two kinds of fibrous tissue differ from each other 

 in many respects, but chiefly in their ultimate structure, 

 their physical properties, and their colour : both are largely 

 employed in those parts subservient to the organs of loco- 

 motion. 



