CARTILAGE. 



703 



Cartilage forms the entire skeleton in some kinds of 

 fishes, the Skate, Lamprey, &c. j and it is nourished with- 



Fig. 833. 



1, Cartilage from Rabbit's ear, showing large cells embedded in a fibrous 

 matrix. 2, Cartilage from Human ribs, with cells in groups, each having a 

 granular nucleus. (Magnified 200 diameters.) 



out coming into direct contact with the blood-vessels, 

 therefore it is said to be non-vascular ; nourishment is 

 derived by imbitionfrom the surround- 

 ing blood-vessels. When examined 

 microscopically, the simplest form of 

 cartilage is seen to resemble in a 

 striking manner the cellular tissue of 

 vegetables ; it consists of an aggre- 

 gation of cells of a spherical or oval 

 form, capable in some cases of being 

 separated from each other, and every 

 cell having a nucleus, with a'nucleolus 

 in its interior. In figs. 332, 333, and 

 334, we have varieties of this structure. 

 In the more highly organized scale 

 of animals, a strong fibrous capsule, 

 or sheath, surrounds the cartilage- 

 cells; some of the fibres dip in amongst 

 the cells, and bind them firmly 

 together. In those inhabitants of the 

 water, the Ray and Shark, the entire skeleton being car- 

 tilaginous, the cell is imbedded in a matrix, which ma* 



Fig. 334. Cartilage from 

 the Cuttle-fish, showing 

 stellate form of cells. 



