122 ARTHROLOGY. 



between the vertebral centra. Stratiform or Investing, when it 

 clothes the part of bones over which the tendons of muscles play, 

 sometimes existing in the tendons themselves. 



This tissue is dullish white, opaque, and, for the most part, 

 devoid of perichondrium ; it is vascular, but its blood-vessels are 

 few, and confined to the fibrous tissue, which exists as interwoven 

 bundles of fibres, with cartilage cells interspersed amongst them. 

 In the variety connecting vertebrae, it consists of concentric rings 

 of fibrous tissue, enclosing a soft elastic centre, partly made up of 

 cartilage cells, and often regarded as the remnant of the notochord. 

 In fishes this portion is soft and pulpy, filling the opposing con- 

 cavities of the vertebral centra. Fibro-cartilage has great power 

 of cohesion, surpassing even that of bone. 



Yellow elastic fibro-cartilage is found in the epiglottis or valve 

 which closes the principal air-tube ; it forms part of the frame- 

 work of the ear, and of the Eustachian tubes which convey air to 

 the tympanum. The fibres forming the matrix are similar to 

 those of yellow elastic tissue. 



Cellular or reticular cartilage is found in the ear of some 

 small rodents, and in the bat. It consists of cells densely packed, 

 and apparently without a matrix ; the walls of the cells thus 

 coming into contact, give it a net-like appearance, hence the name 

 reticular cartilage. 



CONNECTIVE TISSUE. 



In one form or other this tissue is found in all parts of the 

 body. The chief varieties are the areolar and the fibrous ; the 

 former serving as a connecting medium and support to the various 

 organs, and to the structures of which they are formed. It 

 appears as a loose translucent mesh, its interwoven bundles form- 

 ing spaces termed the areolae or cells, hence its name Cellular or 

 Areolar Tissue. It consists of minute Iamina3 and filaments 

 mixed with small fibres of elastic tissue, while cells, or their 

 remains, nuclei and walls, are also present, the whole embedded 

 in a perfectly transparent basis. Other slightly varying forms are 

 termed Retiform, Gelatinous, &c., while the connective tissue of 

 the brain and retina has received the name of Neuroglia. 



White fibrous tissue has a similar structure to the above, but 

 is dense, strong, and practically non-elastic. The filaments which 

 form it are mostly parallel and wavy in their arrangement. It 



