454 BONE, PATHOLOGICAL CONDITIONS OF. 



limited period of our existence, or why even permanently entangled, the periosteum between 



amongst young persons it may occur in one the two can have no share in the reproduction, 



individual and not in another, form questions and yet the whole is united by a cylindrical 



to which, in the present state of our knowledge, shell of bone, on the principle of reproduction 



we can give no answer. We are not even in necrosis. It is also known that compound 



agreed on the different steps of the process or fractures, where the fragments have been exten- 



on the structure principally engaged. sively stripped of periosteum, have united in 



It has been observed that the portion of the the same way, and the regeneration of bone, in 

 bone which is to die, and for some space above these instances, could not be attributed to peri- 

 and below it, is surrounded by a dense thick- osteum, inasmuch as that had been destroyed, 

 ened mass, of rather a gelatinous character ; It must be owned that this is a very unusual 

 that this mass, after a very short time, becomes occurrence in compound fractures, but one sin- 

 opaque in detached spots, and that depositions gle example will be sufficient to prove that the 

 of osseous material are found within it, so that reproduction can take place independently of 

 a case of bone may be constructed around the the periosteum. And again, in cases where 

 original one before it actually dies, and thus disease has caused the sloughing and destruc- 

 the limb never be entirely deprived of support.* tion of the periosteum, as for instance in deeply 

 As soon as the dead bone separates from this seated paroriychia, still reproduction is some- 

 surrounding mass, the internal surface of this times accomplished by a process resembling 

 new material becomes, under some circum- necrosis. These arguments seem to be very 

 stances, covered with a layer of lymph, and decisive in overturning the doctrine of the sur- 

 under others with regular ossific granulations, rounding shell being formed by the periosteum, 

 which gradually increase until a new bone is and accordingly Russell supposed that a depo- 

 formed, nearly as serviceable, though not so sition takes place from all the surrounding 

 symmetrical or so beautiful as the old one. It structures ; that it is at first gelatinous ; that it 

 next becomes a question, what is this gelatinous soon assumes the appearance of cartilage ; and 

 mass, and whence is it derived ? It has been that at the end of twenty-four days bony specks 

 supposed that it was the periosteum of the old may be discovered within it. The external 

 bone swelled and thickened, and at the same surface of this deposit is rough, and attached to 

 time softened in consistence; and this opinion the surrounding parts: its thickness is quite 

 has been strengthened by Dr. Macartney,f the unequal, being greater in proportion to the du- 

 present Professor of Anatomy in the University ration of the disease, and always more so than 

 of Dublin, who stated that he had opportunities the bone it is destined to replace. The internal 

 of watching the progress of the disease from its surface, or that next the old bone, is more 

 earliest periods upwards. According to this smooth, and covered either with lymph or gra- 

 gentleman, " the first and most important cir- nulations. Boyer, Meckel, Weidmann, and 

 cumstance is the change that takes place in the other continental surgeons, attribute the process 

 organization of the periosteum : this membrane nearly altogether to the periosteum, and there- 

 acquires the highest degree of vascularity, be- fore their opinions need not be particularly dis- 

 comes considerably thickened, soft, spongy, and cussed ; but it is proper to mention that all the 

 loosely adherent to the bone ; the cellular sub- very accurate descriptions we read, of the pro- 

 stance, also, which is immediately connected gress from gelatine to cartilage and from carti- 

 with the periosteum, suffers a similar alteration: lage to bone, must be received with the utmost 

 it puts on the appearance of being inflamed, its caution. It is by no means usual to meet with 

 vessels enlarge, lymph is shed into its inter- cases exemplifying these descriptions ; and 

 stices, and it becomes consolidated with the amongst a considerable number of dissections 

 periosteum." Next, " the newly organized pe- of necrosis, it will peihaps be difficult to find 

 riosteum, which, for the sake of distinction, one one in which the existence of cartilage can be 

 might call the vascular sheath or investment, separately and distinctly shown, 

 separates entirely from the bone, after which it Such is an outline of the chief opinions en- 

 begins to remove the latter by absorption, and tertained on this interesting subject, and it is 

 during the time that this process is carrying on, probable that, to a certain extent, they are all 

 the surface of the vascular investment, which is correct. When the periosteum has not been 

 applied to the bone, becomes covered with removed or spoiled, there can be no doubt that 

 little eminences, exactly similar to the granula- it is deeply and even principally engaged in the 

 tions of a common ulcer." To this doctrine process of reproduction. In the museum at 

 Mr: Russell, of Edinburgh, strongly objected. Park-street, the specimens exhibiting the earliest 

 He stated that if the osseous matter was depo- period of the disease show the periosteum as 

 sited between the layers of periosteum, both the slightly thickened, smooth on its internal, but 

 external and internal surfaces of the new de- more rough and flocculent on its external sur- 

 posit ought to be perfectly smooth, whereas the face, detached from the bone, the surface of 

 contrary is observed they are rough, irregular, which is smooth, and scarcely appears changed 

 and one of them is covered with granulations, from its natural and healthy condition. At a 

 He instanced cases of fracture in which, one more advanced period, the periosteum is still 

 fragment overlapping the other, and being thus thicker, but is not softened ; on the contrary, 



it has nearly the firmness of ligament, and 



* See Russell on Necrosis. there are small osseous depositions within it ; 



t See Crowther on White Swelling. Edition tne Done tnen being rough and uneven on its 



1808, p. 183. surface and evidently having lost its vitality. 



