OSSEOUS TISSUE. 



857 



the embryo may be considered the element of 

 the laminae. 



Again, the intercellular tissue found in the 

 embryo forms the medium of connection be- 

 tween the cartilage cells or corpuscles, as 

 they are called, between the primary tubes, where 

 bone is developing, and lastly, becomes thebond 

 of union between the Haversian systems. 



The foregoing description applies to the 

 growth of the shaft of a long bone in the carti- 

 lage connecting it with the epiphysis. 



The laws regulating the growth of the epiphysis 

 in the cartilage which unites it to the shaft of 

 the bone are but a slight modification of those 

 which regulate the growth of the shaft. The 

 cartilage corpuscles, however, here form small 

 rounded groups, and ossification proceeds in 

 the intercellular tissue around them, and the 

 groups themselves eventually form a cavity, by 

 which means the spongy head of the bone is 

 formed. The flat bones are developed much 

 as the long ones, the thin edges of these being 

 tipped with cartilage, which developes its cells, 

 and intercellular tissue. 



A bone at the time of its development is of 

 equal density through the whole diameter at 

 the point where ossification is just perfected. 

 The arrangement of compact and spongy, as 

 seen in the various bones, is an after process 

 which takes place gradually, and in relation to 

 the individual bones of which the framework of 

 the body is composed. 



On considering the process of developement 

 of bone, it will be apparent that the arrange- 

 ment of cells, intercellular tissue, &c. answers 

 the purpose of giving a definite form and 

 arrangement for the future nourishment of the 

 bone, but that osseous tissue is independent of 

 any particular form. Thus intercellular be- 

 comes osseous tissue, as does the tissue of the 

 cells. I wish to lay stress upon this point, as 

 it bears particularly upon the character of 

 certain formations of bone in unnatural 

 situations, or adventitious bone. 



Ossification of permanent cartilage. The 

 cartilages of the larynx at an advanced age are 

 liable to become ossified, and in such cases, as 

 the formation of osseous tissue goes on but 

 slowly, the process may be observed with ease. 

 In this case the corpuscles do not develope 

 others as in temporary cartilage where increase 

 of size is required, but retain their usual 

 appearance. While the osseous granules are 

 developed in the intercorpuscular tissue, at first 

 but few of them are seen, and these spherical 

 and isolated ; they soon, however, become 

 numerous, and unite, thereby forming an osseous 

 mass. The intercellular or intercorpuscular 

 tissue having advanced in ossification, the cor- 

 puscles, or rather their parietes, pass through 

 the same process, and by degrees the whole 

 cartilage becomes converted into bone. 



The formation of the individual gianules is 

 more readily observed in these cartilages than 

 in any other situation. This form of ossifi- 

 cation establishes an interesting and explanatory 

 link of connection between bone and the various 

 osseous plates we find in abnormal situations. 

 For in the latter the spherical granules appear, 



and these, at first few and isolated, and lying 

 amongst the fibres of the tissue, rapidly in- 

 crease in number, unite, and form an osseous 

 mass. 



Osseous plates occur in various soft tissues 

 as the result of deranged action, where in the 

 healthy condition of the part they are not found. 

 Thus we have osseous plates formed in the coats 

 of arteries, in the pleura, in the diaphragm ; 

 also osseous masses in the uterus ; and some- 

 times in the muscular tissue and in the pla- 

 centa. These plates are all formed in the same 

 manner, namely, by the developement of 

 minute spherical osseous granules, which form 

 into a mass, the shape of which is modified by 

 the form of the tissue in which the develope- 

 ment occurs. 



I have examined many of these formations 

 and find them to be composed of true osseous 

 tissue, but not true bone ; for they have not the 

 definite Haversian systems, which, formed of 

 osseous tissue, constitute bone. But they have 

 cavities scattered through them ; these, however, 

 have no definite shape, but assume all kinds of 

 irregular forms, and though they are no doubt 

 necessary to the vitality of the mass, yet their 

 action cannot be very perfect. Spiculse of 

 osseous matter are sometimes met with in 

 cancerous tumours, but here it is very rare to 

 find an Ilaversian system. The osseous plates 

 found in the dura mater are, however, true 

 bone, and are developed like the flat bones. 

 I am decidedly of opinion that these masses 

 are endowed with vitality, and are not mere 

 concretions as some have regarded them, 

 though this vitality is of a low degree. 



Formation of osseous tissue in union of frac- 

 tured bones. Supposing the subject in which 

 the fractures occur to be young, cartilage 

 similar in every respect to temporary cartilage 

 is produced between the fractured extremities 

 of the injured bone. In the centre of this 

 ossification commences, the process being 

 somewhat similar to ossification of permanent 

 cartilage, or holding an intermediate place 

 between that process and the ossification of 

 epiphyses. 



The corpuscles here increase in size but not 

 in number. The ossification commences in 

 the intercellular tissue, and proceeds to the 

 parietes of the cells, thus forming areolse of 

 bone. 



The action may also commence in the carti- 

 lage in contact with the fractured surface. 

 This 1 believe to be the process by which repa- 

 ration is effected in all cases where union of 

 fractured bones takes place, but my experi- 

 ments have been confined to young animals. 



I have examined various cases where union 

 has not been effected in consequence of the 

 patient's advanced age, and the fracture being at 

 the neck of the femur or of the shaft of the same 

 bone. In these I found no cartilage, and but 

 a scanty amount of condensed cellular tissue. 

 In this latter, however, traces of an attempt 

 at repair may generally be found in the pre- 

 sence of osseous matter in granules or granular 

 masses. In these there is no arrangement of 

 tubes or bone-cells of definite character; indeed 



