SECT. 102.] OSSEOUS SYSTEM. 1 89 



§ 102. Alterations in the Ossifying Cartilages. — At the period 

 of the ossification of a cartilage, its cells, which were hitherto 

 small, and contained but few secondary cells, begin to enlarge, 

 and new generations of cells are successively produced from the 

 previously existing ones. This active vegetative process also 

 manifests itself at the ossifying borders of the bones, which arc 

 already developed to some extent, where the cells next to the 

 bone are found to be larger, and are smaller the further they are 

 removed from it. All cells about to become ossified, possess only 

 moderately thick capsules, and a distinct primordial utricle (car- 

 tilage-cell) with clear, rarely somewhat granular contents, along 

 with a distinct vesicular round nucleus, possessing a nucleolus and 

 readily distinguishable walls. They alter, however, very quickly 

 on the addition of water, acetic acid or alcohol, or by dessication, 

 etc., the contents and membrane of the primordial utricle con- 

 tracting around the nucleus, and forming a rounded, elongated, 

 dentated, even stellate, granular, dark body (cartilage-corpuscle 

 of authors). Their size and the manner in which they are grouped, 

 varies not inconsiderably according to age and locality. With 

 regard to the first point, they exhibit a continual increase during 

 embryonic life, whilst after birth, their size appears to remain 

 nearly the same. With reference to arrangement, it is a law, 

 that wherever cartilages ossify only in one direction, the cells, at 

 the border of the bone, are arranged in rows. As has been long- 

 known, this is best marked at the ends of the diaphyses of cylin- 

 drical bones, where the rows lie very beautifully and regularly 

 parallel to each other, and are of considerable length. This 

 arrangement may also be seen in many other places, as soon as 

 cartilages ossify only in one direction, as, for instance, upon the 

 surfaces of connection of the vertebrae. Where, on the other hand, 

 the osseous centres in the midst of a cartilage, enlarge in all 

 directions, the cartilage- cells are gathered into rounded, or oblong, 

 irregularly scattered groups, as in the short bones at the time of 

 their commencement, and in the epiphyses. 



By closely comparing the cells which lie nearer, and those further 

 removed from, the borders of ossification, and the separate groups 

 which they form, it becomes evident, that their peculiar arrange- 

 ment is directly connected with the manner of their multiplication. 

 Every separate group (or two) corresponds, in a certain measure, 

 to a single original cell, and represents all the descendants which, 

 in the course of development, have sprung from the latter. Now, 

 in some cases, all these newly-formed cells are disposed in one or 



