WHITE AND YELLOW PIBKOUS TISSUE. 



603 



ments, with a dark decided border ; which are disposed to curl 

 when not put on the stretch (Fig. 318). They are for the 

 most part between l-5000th and l-10,000th of an inch in 

 diameter ; but they are often met with both larger and smaller. 

 They frequently anastomose, so as to form a network. This 

 tissue does not undergo any change, when treated with acetic 



FiQ. 316. 



Fw. 317. 



Fibrous membrane from Egg-shell. 



WhiU M'ibrous Tissue from Ligament. 



FiO. 318. 



acid. It exists alone (that is, without any mixture of the white) 

 in parts which require a peculiar elasticity, such as the middle 

 coat of the Arteries, the Vocal Cords, the "ligamentum nuchse" 

 of Quadrupeds, the elastic liga- 

 ment which holds together the 

 valves of a Bivalve shell, and 

 that by which the claws of 

 the Feline tribe are retracted 

 when not in use ; and it enters 

 largely into the composition 

 of Areolar tissue. This con- 

 sists of a network of minute 

 fibres and bands, which are 

 interwoven in every direction, 

 so as to leave innumerable 

 areola or little spaces, which 

 communicate freely with one 

 another. Of these fibres, some 

 are of the yellow or elastic kind ; but the majority are composed 

 of the white fibrous tissue ; and, as in that form of elementary 

 structure, they frequently present the form of broad flattened 

 bands, or membranous shreds, in which no distinct fibrous ar- 

 rangement is visible. The proportion of the two forms varies, 

 according to the amount of elasticity, or of simple resisting 

 power, which the endowments of the part may require. _ We 

 find this tissue in a very large proportion of the bodies of higher 

 Animals; thus it binds together the ultimate fibres of the 

 muscles and nerves into minute fasciculi, unites these fasciculi 

 into larger ones, these again into still larger ones which are 



TeUow Fibrous Tissue from Ligamentum Nuchas 

 of Calf. 



