120 



STRUCTURE AND ENDOWMENTS OF ANIMAL TISSUES. 



the interweaving of bundles of fibres in different directions. In the 

 Fibro- Cartilages, we find a mixture of the characteristic structure of 

 Ligament with that of Cartilage ; bundles of fibres, similar to those 

 which constitute the former, being disposed among the cells which are 

 the chief organized constituents of the latter. In certain Fibro-Carti- 

 lages, however, these fibres are endowed with a high degree of elasticity. 



189. These two qualities, that of resistance to tension without any 

 yielding and that of resistance combined with elasticity, are charac- 

 teristic of two distinct forms of Fibrous tissue, the White and the Yellow. 

 The White Fibrous tissue presents itself under various forms, being some- 

 times composed of fibres so minute as to be scarcely distinguishable ; 

 and sometimes presenting itself under the aspect of bands, usually of a 

 flattened form, and attaining the breadth of l-500th of an inch. These 

 bands are marked by numerous longitudinal streaks, but they cannot be 

 torn up into minute fibres of determinate size ; hence they must be re- 

 garded as made up of an aggregation of the same elements as those 

 which may become developed into separate fibres. The fibres and bands 

 are occasionally somewhat wavy in their direction. The tissue, which is 

 perfectly inelastic, is easily distinguished from the other by the effect of 

 Acetic acid, which swells it up, and renders it transparent, at the same 

 time bringing into view certain oval corpuscles, which are supposed to 

 be the nuclei of the cells that were concerned in the formation of the 

 tissue. 



190. The Yellow Fibrous tissue exists in the form of long, single, 

 elastic, branched filaments, with a dark decided border, which are dis- 

 posed to curl when not put on the stretch. 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, as shown in Fig. 6. This tissue does not un- 



Fig. 5. 



Fig. 6. 



Fasciculus of fibres of white fibrous tissue: 

 from lateral ligament of knee joint. 



Yellow fibrous tissue from ligamentum 

 nuchos; a, the fibres drawn apart, to show 

 their reticulate arrangement; b, the fibres 

 in situ. 



dergo any change, when treated with acetic 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 Chordae Vocales, 

 the Ligamentum Nuchse (of Quadrupeds) and the Ligamenta subflava ; 

 it enters largely into the composition of certain parts, which are com- 



