200 



OSSEOUS SYSTEM. 



[sect. 104. 



has been produced, to which, then, the epiphysal nuclei E 4 E 4 , 

 likewise originating in the cartilage, are added, whilst in its 

 growth in thickness, the cylindrical layers P, P 1 , P", P 3 which 

 become continually longer and, in the middle, thicker, are con- 

 cerned. In such a cylindrical bone, 

 accordingly, all the part formed 

 from cartilage has the form of a 

 double cone with rounded bases, 

 the part deposited from the perios- 

 teum 1, 2, 3, 4, P 3 , and 1', 2', 3',4'P 3 , 

 that of a long tube thickest in the 

 middle, similar to an elongated ver- 

 tebra of a fish with conically de- 

 pressed end surfaces. The articu- 

 lar cartilage Gr is the non- ossified 

 remains of the epiphysal cartilage 

 and the medullary cavity not ex- 

 hibited in the figure (it can be 

 imagined as nearly indicated by the 

 contours of the fourth bone E 3 E 3 ) 

 has arisen by the absorption of the 

 whole osseous substance developed 

 from the cartilage and periosteum ; 

 in this case the first three EE, E^ 1 

 and E"E 2 . m In the cylindrical bones 

 without a medullary cavity, and 

 in all others which  contain only 

 spongy substance in their interior, 

 the absorption does not advance 

 nearly so far as in the above- 

 described cases; that is to say, it 

 proceeds only to the production of 

 a loose spongy substance in the 

 interior, and we find accordingly, 

 for instance in the vertebrae, still 

 more or less considerable remains 

 of the earlier bone deposits, even of 

 those which have arisen from the 

 ossification of cartilage. The ab- 

 sorption here also affects not only 

 the osseous nucleus formed from 

 the cartilage, but also the periosteal 



Diagram of the growth of a tubular 

 bone. 15. First rudiment in the diaphysis 

 already ossified with cartilaginous epi- 

 physes. A. The same bone with four 

 additional stages of development, EPl'E 1 , 

 E*P>piE 2 , E 3 m v -E 3 , E 4 P 3 r=E 4 . PP'P-P3 

 periosteal layers of these four bones, 

 'the space between 1,2,3,4, and l',2', 

 3', 4', indicates parts which in the 

 largest bone have originated from car- 

 tilage. E'E 1 . Cartilaginous epiphyses of 

 the second bone. E'E 2 , Epiphyses of 

 the third bone with bone-nuclei. E 3 E 3 , 

 E'E'. Epiphyses of the fourth and fifth 

 bones with larger epiphysal nuclei. G. 

 Articular cartilage. I.E. Interstitial 

 cartilage between the bony epiphyses 

 and diaphyses. 



