PEKICHONDEIUM OF CARTILAGE. 125 



deposition of the calcareous matter can be explained 

 by physics, and can be imitated out of the body, but 

 the matrix which is formed cannot be produced 

 artificially. This last results from changes which oc- 

 curred while the matter of which it consists waa in 

 the state of living matter, or bioplasm. 



m. Perichoiidriuni of cartilage. — The external 

 limitary structure of membraniform cartilage called 

 perichondrium is distinctly fibrous, with elongated 

 masses of bioplasm here and there which were con- 

 cerned in its formation. Beneath the perichondrium 

 are larger masses of bioplasm, which assume more 

 and more the character of those belonging to cartilage 

 as we recede from the surface. It is immediately 

 beneath the perichondrium in growing cartilage that 

 the chief maltiplication of the masses of bioplasm 

 takes place, and masses which at one time belong to 

 the perichondrium, at a later period are surrounded 

 by the cartilage tissue which they have gradually 

 produced. Near the surface of the perichondrium 

 the vessels and nerves are distributed. It is only 

 when cartilage is very thick that vessels are found 

 distributed ui its substance. 



m.* Cellular cartilage from the Mouse's ear. — 

 Some forms of cartilage ai-e said to be destitute of 

 matrix or intercellular substance, and to consist of 

 " cells " only. The thin part of the ear of a young 

 white mouse will aflford a good example of what has 

 been termed purely cellular cartilage. Very young 

 cells or elementary parts may be seen in the course 

 of formation. The bioplasm of these is very distinct, 

 and lies upon the surface of the formed material, 

 which is seen as a vesicle of delicate transparent 

 tissue. This form of cartilage is formed somewhat 

 differently from ordinary cartilaginous tissue, for the 

 formed material corresponding to each mass of bio- 

 plasm is distinct from that of adjacent masses. 

 Instead of expanding uniformly in all directions as it 



