TISSUES. 77 



physis pubis, and in the insertion of the round 

 ligament. 



General Considerations. Cartilage tumors are 

 known as chondroma, and are common. Like 

 cartilage they are of slow growth and therefore 

 harmless. The absence of blood accounts, in large 

 part for the inactivity of the cartilage cells, both in 

 the normal and pathological condition. Further- 

 more, cartilage cells are enclosed in the matrix in a 

 manner that inhibit their multiplication. Cartilage 

 therefore grows by apposition or acquisition, not by 

 intussusception, like most tissues. 



Cartilage slowly ossifies with age. During this 

 process loops of blood-vessels enter the matrix from 

 the perichondrium, and lime salts are deposited ad- 

 jacent to the cartilage cells. This process will be 

 -further described under bone development. 



The identification of cartilage is very easy, as the 

 matrix has a marked affinity for many stains. 

 3. BONE. 



Bone is the chief supporting tissue of the body, 

 and consists of a calcified intercellular substance, 

 mostly calcium phosphate, and connective-tissue 

 cells, or bone cells. Organic substance constitutes 

 one-third the weight, and inorganic substance two- 

 thirds the weight of bone. The bone cells, some- 

 times called bone corpuscles, are flattened stellate 

 cells with many slender processes, and a well defined 

 round or oval nucleus. Like cartilage cells they lie 

 imbedded in lenticular spaces called lacuna. These 

 lacunae, however, communicate with adjacent la- 

 cunae by means of numerous capillary tubes called 



