274 



OP THE PRIMARY TISSUES OF THE HUMAN BODY. 



sition, from the permanent. They present the same irregular scattering of cells 

 through a homogeneous intercellular substance; and there is the same absence 

 of any vascularity in the cartilaginous tissue itself. In all considerable masses, 

 however, we find a coarse network of canals, lined by an extension of the peri- 

 chondrium or investing membrane ; and these canals, which may be regarded as 



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Transverse section of Cartilage close to the plane of Ossification. 

 Fig. 67. Fig. 68. 



Vertical Section through the Carti- 

 lage and incipient Done of the diaphysia 

 of the Femur, in an Infant a fortnight 

 old : a, cartilage-cells arranged in lon- 

 gitudinal piles near the ossified surface ; 

 b, plane of ossification, the osseous mat- 

 ter inclosing the bases of the piles ; c, 

 close osseous network first formed ; d, 

 cancellated structure formed by the ab- 

 sorption of parts of this ; e, its cancelli, 

 filled with medulla. 



Vertical section of Cartilage at ttie seat of Ossifica- 

 tion ; the clusters of cells are arranged in columns, 

 the intercellular spaces between them being 1- 

 3250th of an inch in breadth. At the lower end of 

 the figure, osseous fibres are seen occupying the 

 intercellular spaces, at first bounding the clusters 

 laterally, then splitting them longitudinally and 

 encircling each separate cell. The greater opacity 

 of this portion is due to a threefold cause ; the in- 

 crease of osseous fibres, the opacity of the contents 

 of the cells, and the multiplication of oil-globules. 



