CONNECTIVE TISSUES 51 



in the wall of the ileum (the terminal portion of small 

 intestines which opens into the cecum) . Lymph nodes 

 (glands). (See Lymphatic System.) 



8. Cartilage. Cartilage is not as compact or strong 

 as bone. It is more yielding; thus it will be found in 

 different parts of the body when this firm yet pliable 

 property is essential to the function of an organ. We 

 see it in the cartilages of the larynx, where one may 

 readily understand how its structure must be more or 

 less elastic owing to the constant action of the muscles 

 upon the cartilages and their change in relationship 

 during talking, singing, etc., and its value can be 

 appreciated when placed between bones, as a shock 

 absorber; demonstrated by the intervertebral disks 

 between each vertebra. 



In studying the structures of cartilage it is con- 

 sidered under perichondrium, cells, and intercellular 

 substance. The perichondrium is a fibrous sheath 

 which surrounds cartilage and corresponds to the 

 periosteum of bone. It is divided into an outer fibrous 

 layer containing few cells, and an inner portion or 

 chondrogenetic layer, consisting of flattened and elon- 

 gated or spindle-shaped cells. These are the chondro- 

 blasts or cartilage cells. The latter cells are seen just 

 beneath the perichondrium, where they appear as flat 

 cells, then as the centre of the cartilage is reached 

 they become more oval or even round. Each cell is 

 rich in protoplasm and contains one or more vacuoles. 

 The cell is surrounded by a capsule, and a small space 

 intervenes, between the cell and the capsule called 

 a lacuna. The intercellular substance consists of a 

 homogeneous mass in the hyaline cartilage, and of 

 white fibrous and yellow elastic fibers, in the white 

 fibrocartilage and yellow fibrocartilage respectively. 



There are three varieties of cartilage: Hyaline, 

 white fibrocartilage, and yellow fibro or elastic. 



The hyaline cartilage is pearl blue in color, is elastic, 

 and cuts with a knife. It is found in the body covering 



