126 SPONGY CARTILAGES. 



grows, it forms a thin lamina whicli increases quickly 

 in extent by the formation of new cells at its free 

 edges. Its increase in thickness is very slight in 

 compax-ison with its increase in extent, and takes 

 place very slowly. 



118. Spongy cartilages. — In the spongy cartilages, 

 as, for example, the epiglottis and some of the other 

 cartilages about the vocal apparatus, are many fibres 

 which possess the reaction of yellow elastic tissue. 

 Of these many are very fine, and so arranged as to 

 form the boundaries of oval spaces, in each of which 

 a mass of bioplasm is lodged. This is often angular, 

 and from the angles delicate fibres may be traced, 

 which are at length lost amongst the plexuses of 

 those which form the tissue itself. It is probable 

 that these masses of bioplasm slowly move round the 

 cavity, and form the deUcate interlacing fibres which 

 accumulate, and constitute the elastic walls of the 

 oval and circular spaces characteristic of this form of 

 tissue. 



Few who have not examined specimens prepared 

 according to the method I have described will, I fear, 

 accept the \aew of the structure and formation of the 

 tissue here given. It is strongly opposed to the doc- 

 trines generally taught, which have been arrived at 

 from studying sections immersed in water, serum, or 

 other limpid fluid, in which however it is not possible 

 to discern the real arrangement of the elements of the 

 texture. 



llO. Fitoro-cartilage. — A.lthough this tissue, in its 

 fully developed state, differs remarkably in structure 

 and properties both from fibrous tissue and cartilage, 

 at an early period of development some forms of it 

 could not be distinguished from embryonic cal'tHage. 

 The fibro-cartilage of the vertebral discs, at an early 

 period of formation, approximates very closely to 

 certain forms of fibrous tissue. In all cases bioplasm 

 takes part in the formation of the fibrous-like 



