40 



CELL DIFFERENTIATION AND THE ELEMENTARY TISSUES 



be shown to be made up of fibers, comparable with those found in white 

 fibrous tissue, embedded in the homogeneous matrix. 



In the hyaline cartilage of the ribs the cells are mostly larger than in 

 the articular variety and there is a tendency to the development of fibers 



FIG. 50. Yellow Elastic Cartilage of the Ear. Highly magnified. (Hertwig.) 



in the matrix, figure 49. The costal cartilages also frequently become calcified 

 in old age, as also do some of those of the larynx. 



In the fetus cartilage is the material of which the bones are first con- 

 structed; the "model" of each bone being laid down, so to speak, in this 



FIG. 51. White Fibro- Cartilage. (Cadiat.) 



substance. In such cases the cartilage is termed temporary. It closely 

 resembles the ordinary hyaline cartilage but the cells are more uniformly 

 distributed throughout the matrix. 



