46 



GENERAL ANATOMY. 



which the elastic fibres greatly preponderate, to the almost complete exclusion of 

 the white fibrous element. It is found in this condition in the ligamenta subflava, 

 in the vocal cords, in the longitudinal coat of the trachea and bronchi, in the 

 inner coats of the blood-vessels, especially the larger arteries, and to a very con- 



pn 



FIG. 14. Connective tissue. (Klein and 

 Noble Smith.) a. The white fibrous element 

 a layer of more or less sharply-outlined .paral- 

 lel, wavy bundles of connective-tissue fibrils. 

 On the surface of this layer is b, a network of 

 fine elastic fibres. 



FIG. 15. Tendon of mouse's tail, stained 

 with haematoxylin, showing chains of cells 

 between the tendon-bundles. (From Quain's 

 Anatomy. E. A. Schafer.) 



siderable extent in the thyro-hyoid, crico-thyroid, and stylo-hyoid ligaments. It 

 is also found in the ligamentum nuchse of the lower animals. When viewed 

 under the microscope (Fig. 16) it is seen to consist of an aggregation of curling 

 fibres, with a well-defined outline. They are considerably larger in size than the 

 fibrillse of the white fibrous element, and vary much, being from the -^^o "o * tne 

 j-oVo of an inch in diameter. The fibres form bold and wide curves, branch and 

 freely anastomose with each other. They are homogeneous in appearance, and 

 have a tendency to curl up, especially at their broken ends. In some parts, where 

 the fibres are broad and large and the network close, the tissue presents the 

 appearance of a membrane, with gaps or perforations corresponding to the inter- 

 vening space. This is to be found in the inner coat of the arteries, and to it the 

 name of fenestrated membrane has been given by Henle. The yellow elastic fibres 

 remain unaltered by acetic acid. 



Areolar tissue is so called because its meshes are easily distended, and thus 

 separated into areolae or spaces, which all open freely into each other, and are 

 consequently easily blown up with air, or permeated by fluid when injected into 

 any part of the tissue. Such spaces, however, do not exist in the natural con- 

 dition of the body, but the whole tissue forms one unbroken membrane com- 

 posed, of a number of interlacing fibres, variously superimposed. Hence the 

 term "the cellular membrane " is in many parts of the body more appropriate 

 than its more modern equivalent. The chief use of the areolar tissue is to bind 

 parts together, while by the laxity of its fibres and the permeability of its areolse 

 it allows them to move on each other, and affords a ready exit for inflammatory 

 and other effused fluids. It is one of the most extensively distributed of all the 

 tissues in the body. It is found beneath the skin in a continuous layer all over 

 the body, connecting it to the subjacent parts. In the same way it is situated 

 beneath the mucous and serous membranes. It is also found between muscles, 

 vessels, and nerves, forming investing sheaths for them, and connecting them 

 with surrounding structures. In addition to this, it is found in the interior of 

 organs, binding together the various lobes and lobules of the compound glands, 



