FIBROUS<MEMERANES AND “LIGAMENTS. 41 
strain has to be borne. This is the case with the Ligaments, 
hich bind together the bones at the joints, the Zendons, by 
“which the muscles are usually attached to the bones, and the 
tough Fibrous Membranes that envelope and protect many 
of the most important viscera. In these any considerable 
amount of elasticity would be misplaced ; and we conse- 
_ quently find that they are chiefly or entirely composed of the 
‘white fibrous tissue. Whenever an elastic ligament is re- 
quired, however, we find the white replaced by yellow. One 
of the best examples of this is seen in the ligament of the 
meck of many quadrupeds, commonly known as the pazy- 
| waxy; which is given to the large herbivorous quadrupeds, 
| such as the ox, to assist them in supporting their heavy 
heads with as little exertion as possible ; whilst carnivorous 
"quadrupeds, such as the lion and tiger, are endowed with it 
jens in their mouths. In Man we scarcely find a trace of 
it. This yellow fibrous tissue is found, moreover, in the walls 
| of the arteries (§ 248), to which it gives their peculiar elas- 
) ticity ; and it also forms the vocal cords of the larynx (§ 681). 
the Feline tribe are drawn back into their sheaths when not 
im use, being projected (when required) by muscular action ; 
and that the two pieces of the shell of Bivalve Mollusks are 
anited at the hinge, and are at the same time kept apart for 
the admission of water between them, except when the 
nimal forcibly draws them together by its adductor muscle 
30. All these fibrous tissues, then, are concerned in actions 
ly mechanical ; and there is nothing in their properties 
which is so distinct from those of inorganic substances, as to 
Tequire to be considered as vital We may consider them, 
therefore, as among the lowest forms of animal tissue; and 
cordingly we find that, when the higher forms degenerate 
r waste away, these appear in their place. Such a degene- 
ation may take place simply from want of use. Thus if, 
tom palsy or want of power of the nerves, the muscles of 
ihe legs are disused for several years, they will lose their 
eculiar property of contractility ($ 5); and it will be found 
bat scarcely any true muscular structure remains, but that it 
‘Teplaced by some form of fibrous tissue. Or again, if the 
