PRIMARY TISSUES : SIMPLE FIBROUS TISSUES. 



37 



merely to the physical actions of the framework ; as, for ex- 

 ample, by holding its parts together, by communicating motion, 

 or by giving them mechanical support and protection. The 

 several parts of the body, even to the very minute divisions 

 of its organs, are held together by what may be termed, in 

 contradistinction to Muscular and Nervous fibre, the simple 

 fibrous tissues ; and these are merely endowed, like ordinary 

 cords, with the power of resisting tension or strain, either 

 without themselves yielding to it at all, or with a certain 

 amount of elasticity, which enables them first to yield to 

 a certain degree, and then to recover their previous state. 

 These two qualities are characteristic of two distinct forms of 

 simple fibrous tissue, the white and the yellow. 



23. The White fibrous tissue presents itself under various 

 forms, being sometimes composed of fibres so minute as to be 

 scarcely distinguishable, but 

 more commonly presenting 

 itself under the aspect of 

 flattened bands, which are 

 but imperfectly divided into 

 fibres, and have more or less 

 of a wavy aspect (fig. 1). This 

 tissue is resolved, by long 

 boiling, into gelatine ; and 

 when treated with acetic acid, 

 it swells up and becomes 

 transparent, by which peculiarity it can be readily dis- 

 tinguished from the other kind, to be next described. The 

 Yellow fibrous tissue presents 

 itself in the form of long, 

 separate, clearly defined fibres, 

 which sometimes branch, and 

 which break short off when 

 overstrained, their extremi- 

 ties being disposed to curl up 

 (fig. 2). They are, for the most 

 part, between 1-5, 000th and 

 1-1 0,000th of an inch in 

 diameter ; but they are often Fig - 2 -- Y * MO * FIBROUS TISSUE. 

 met with both larger and smaller. This kind of tissue un- 

 dergoes but very little change from long boiling, and it is 



Fig. 1. WHITE FIBROUS TISSUE. 



