SIMPLE FIBROUS TISSUES. 



121 



7. 



monly regarded as Cartilaginous, such as the external ear ; and it is also 

 a principal component of other tissues to be presently described. 



191. These tissues are very different in Chemical composition. Those 

 which are composed of the White fibrous element, namely, Tendons, 

 Ligaments, &c. are almost entirely resolved by long boiling into Gela- 

 tine; and this substance is also largely obtained from the Skin, and 

 from Mucous and Serous membranes, of which, as we shall presently 

 see, that element is a principal component ; whilst it is also yielded in 



; great quantity by Bones, whose animal basis is almost entirely gelatinous. 



192. The composition of the Yellow fibrous tissue appears to be alto- 

 gether dissimilar. It scarcely undergoes any change by prolonged boil- 



: ing ; it is unaffected also by the weaker acids ; and it preserves its 

 elasticity, if kept moist, for an almost unlimited period. According to 



; Scherer, it consists of 48 Carbon, 38 Hydrogen, 6 Nitrogen, and 16 

 Oxygen ; and he considers it to be composed of an atom of Proteine 

 with two atoms of water. (See 171.) 



193. The simple Fibrous tissues appear to be 

 | very little susceptible of change in the living body ; 

 I and we find them very sparingly supplied with 

 i blood-vessels. In the solid Tendons, the bundles 

 I of straight parallel fibres are a little separated 



from each other by the intervention of the Areolar 



! tissue to be presently noticed ;. and this permits 

 the sparing access of vessels to their interior. In 



! the Fibrous Membranes and Ligaments, this is 



i found in somewhat larger amount ; and the vascu- 

 larity of these tissues is rather greater. Two dif- 

 ferent views of their mode of development have 



: been taken by those who have studied it. By some 

 it has been maintained that the White fibres are 

 first developed as cells, which progressively be- 

 come elongated and solidified ; their nuclei at the 



i same time disappearing, until brought into view 



1 by acetic acid (Fig. 7) ; and the Yellow fibres have 

 been supposed to have a similar origin. By others 

 it has been considered that the White fibres are produced by the direct 



I fibrillation of a blastema or plastic exudation ( 181), and that the Yellow 



1 proceed from the nuclear particles which this contains ; no development 

 of cells being requisite for the production of either. The recent inqui- 

 ries of Mr. Paget and others tends to show that both these methods are 

 adopted in the production of the fibrous tissue which is developed for 

 the repair of injuries in the adult body ; the former being seen in the 

 reparation of external wounds to which air has access ; the latter in the 

 organization of " coagulable lymph" effused into internal- cavities, or 

 into the interstices of tissue, altogether secluded from it. 



.94.^ The great use of the foregoing tissues appears to be, to afford a 

 firm resistance to tension ; by which they may either communicate motion, 

 as in the case of Tendons ; or restrain it, as in the case of Ligaments ; 

 or altogether prevent it, as in the case of Aponeuroses and Fibrous 

 Membranes. With this firm resistance, a considerable amount of elas- 



Development of fibres from 

 cells: a, circular or oval nu- 

 cleated cells; 6, the same be- 

 coming pointed; c, the same 

 become fusiform, the nuclei 

 being still apparent; d, the 

 same elongating into fibres, 

 the nuclei having disappeared. 



