45 



VIII. — On a peculiar form of Elastic Tissue found in the Ligamentum 

 Nucha of the Giraffe. By John Quekett, Esq., Assistant 

 Conservator of the Museum, and Demonstrator of Histology 

 at the Eoyal College of Surgeons of England. 



(Bead April 25th, 1849.) 



Two kinds of fibrous tissue, viz., the white and the yellow, are now 

 familiar to most anatomists. They differ from each other in many 

 respects, but chiefly in their ultimate structure, their physical pro- 

 perties, and their colour ; both are largely employed in the animal 

 economy, but principally in those parts subservient to the functions 

 of locomotion. 



The white fibrous tissue is (when perfectly cleared of the areolar) 

 of a silvery lustre, and is composed of bundles of fibres running for 

 the most part in a parallel direction, but if there be more than one 

 plane of fibres they often cross or interlace with each other ; in some 

 specimens it is difficult to make out the fibres distinctly except in 

 certain lights, and in these cases it appears that this tissue may be 

 composed of a longitudinally striated membrane, which may now and 

 then split up into fibres. 



The white fibrous tissue is principally employed in the formation 

 of ligaments and tendons, a purpose for which it is admirably fitted 

 on account of its inelasticity ; it also is concerned in the formation 

 of fibrous membranes, viz., the pericardium, dura mater, periosteum, 

 perichondrium, the sclerotic coat of the eye, and all the different 

 fasciae. 



It is sparingly supplied with blood-vessels and nerves ; the former 

 always run in the areolar tissue connecting the bundles of fibres to- 

 gether, but in the generality of the fibrous tissues the blood-vessels 

 are not well seen except in the dura mater and in the periosteum. 



The yellow fibrous tissue is highly elastic ; it consists of bundles of 

 fibres covered with and connected together by areolar tissue; the 

 fibres are of a yellow colour, in some cases round, in others flat- 

 tened; they are not always parallel, but frequently bifurcate and 

 anastomose with other neighbouring fibres. It is always rather 

 difficult to separate the fibres from each other, and when they are 

 separated, the elasticity of each individual fibre is shown by its 



