CARTILAGE. 



Cartilage forms the entire skeleton in some kinds of 

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



Fig. 303. 



1, Cartilage from Rabbit's ear, showing large cells imbedded 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 imbition from 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. 302, 303, and 

 304, 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 pi g . 304 cartilage from 

 the cells, mid bind them firmly ftafftftSj** 

 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 may 

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