vii CARTILAGE 115 



Thus connective-tissue consists partly of cells, but 

 between these, and forming the main substance of the 

 tissue, is a matrix or intercellular substance, enclosing 

 fibres. In the embryo the tissue consists of closely 

 packed cells, but, as development proceeds, these 

 separate from one another, and the ground-substance 

 is formed between them. 



Cartilage. The ordinary clear or hyaline variety of 

 this tissue is conveniently studied by examining a piece 

 of the thin edge of the omo- or xiphi-sternum, or by 



f l A 

 IW G 



ry. 



o 



c' 



FIG. 34. Section of cartilage, from the head of the Frog's femur, (x 200.) 

 c. cells ; c'. cells undergoing fission ; c. s. empty cell-space ; m. matrix. 



taking a thin section with a razor of the head of the 

 humerus or femur. 



Cartilage consists of a tough, elastic, transparent, 

 homogeneous matrix (Fig. 34, m) containing numerous 

 cavities or cell-spaces (c. s), in each of which is a nucleated 

 cell (c). The cell-spaces, or lacuna, are in many cases 

 arranged in groups of two or four, sometimes close 

 together, sometimes with a narrow space of matrix or 

 intercellular substance between them. This is due to 

 Ithe fact that cartilage grows by the cells undergoing 



i 2 



