SECT. 100.] OSSEOUS SYSTEM. I 87 



Although the development of the osseous tissue has often been treated of, 

 yet the manner in which the bones originate as organs has met with but 

 little attention; and in 1849 and 1850, JET. Meyer and I were the first to 

 follow them in detail, after the principal features had been ascertained in 

 18+6-47 by Tomes, Sharpey, lion-man and me {Zurich. Mitth. i.j>. 168). Quite 

 recently, Bruch, Virchow, Brandt, Tomes and Dc Morgan, and II. Midler, have 

 furnished valuable additions. 



§ 100. The original cartilage-skeleton of the human body is less 

 complete than the subsequent bony one, but is, nevertheless, 

 tolerably well developed. We find, as parts of it, 1, a complete 

 vertebral column, with the same number of vertebrse as in the 

 osseous one, with cartilaginous processes and intervertebral liga- 

 ments; 2, cartilaginous ribs, and a cartilaginous, non-segmented 

 sternum ; 3, entirely cartilaginous extremities, of the same num- 

 ber and external form as the subsequent bones, with the single 

 exception of the pelvic cartilage, which constitutes a single mass, 

 and the clavicle, which never exists in the cartilaginous state 

 {Bruch) ; 4, an imperfect cartilaginous skull. This so-called 

 primordial cranium forms originally a continuous cartilaginous 

 substance, corresponding chiefly to the occipital bone (with ex- 

 ception of the upper half of the flat portion) , the sphenoid bone 

 (except the external lamina of the pterygoid process), the mastoid 

 and petrous portions of the temporal, the ethmoid, the inferior 

 turbinate, the ossicles of the ear and the hyoid bone. It also 

 contains some cartilaginous parts which never ossify; these either 

 remain in this condition during the whole period of life, as the 

 most of the cartilage of the nose, and the lesser cornua of the 

 hyoid bone, or subsequently disappear, as is the case with what 

 is named Meckel's process ; also two cartilaginous lamellae beneath 

 the nasal bones, and a slender cartilage which connects the styloid 

 process with the hyoid bone. Consequently, the vault of the 

 skull, and almost the whole of the lateral portions are absent in 

 the human cartilaginous cranium; further, almost all the part 

 subsequently occupied by the facial bones ; but at the parts not 

 formed from cartilage, the cranium is closed in and completed by 

 a fibrous membrane, which is but a further development of the 

 primitive soft skull-capsule. Thus the skull, although only in 

 part cartilaginous, is as complete at this period as formerly, and 

 in this respect still corresponds to its original condition. The 

 cranium is more completely formed of cartilage in some qua- 

 drupeds, as, for example, in the pig and mouse (see my Mihrosc. 

 Anat.). 



