52 



ZOOLOGY. 



dissection consists to a large extent in the cutting and tear- 

 ing of the connective tissue that binds the organs together. 

 A very good example of areolar tissue may be found under 

 the skin of the rabbit, especially in the region of the armpits. 

 In particular positions the connective tissue is found to 

 have special characters adapted to its circumstances. Thus 

 where the tissue has to transmit a strong pull, the white 

 inelastic fibres are especially abundant, the tissue becomes 

 strong and unyielding and is called aJendfllL- Tendons most 

 frequently connect muscle to bone. On the other hand, if it 

 is subjected to frequent strains, the yellow elastic fibres are 

 abundant, and we have elastic tissue, as at many joints and 

 in the walls of arteries. The form of the corpuscles also 

 varies in these different kinds of connective tissue. 



8. Cartilage. In this we also have cells (cartilage- 

 corpuscles) and a matrix, but the latter contains, instead of 

 gelatin, a substance of similar chemical composition called 

 chondrin, which is far firmer and more elastic. Hence 

 there are usually no fibres in cartilage, which is then called 

 hyaline cartilage from its translucency (e.g. the cartilage 

 at the ends of the limb-bones or that of the trachea). When 



fibres, either white or 

 yellow, are present, we 

 have fibre-cartilage (as e.g. 

 in the intervertebral bodies 

 [chap, vii., 3] or some of 

 the cartilages of the larynx). 

 Another apparent pecu- 

 liarity of chondrin is its 

 ready permeability to 

 liquids : no blood-vessels 

 of any kind are found in 

 the matrix of cartilage^ 

 even when it is an inch 

 or so thick. Fet it is 



Fig 15. CARTILAGE. , . , , , .., 



obvious that the cartilage- 

 corpuscles are not cut off from nourishment, since they 

 are found, not only living and healthy, but often actively 

 growing and dividing (see fig. 15). 



