TO FORM NEW BONE. 



161 



In the fore-legs of dogs and rabbits, there ai-e two bones of nearly equal size, 

 and so connected, that a large portion of one may be taken away without destroy- 

 ing the rigidity of the hmb. There is here, therefore, a convenient opportunity of 

 trying what can be done by the extremities of a bone for restoring losses of sub- 

 stance in its shaft. Experiments of this kind have accordingly been frequently 

 performed on these animals, and the result has uniformly been, that when the 

 portion removed exceeded an inch in length, there was a permanent deficiency of 

 osseous substance, the ends of the bone being merely produced towards each other 

 in a conical form, and connected together by a tough ligamentous texture. Sir 

 A. Cooper has given representations of the results he met with ; and on the 

 table there is a specimen of my oa\ti experience (see Fig. 1, Plate IX). 



Some of those pathologists who deny the ossific power of the periosteum, and 

 claim the whole production of new osseous substance for the bone itself, have at- 

 tempted to explain away the difficulties which have just been stated, by supposing, 

 that in cases of necrosis where a new bone is formed, the old one, in consequence of 

 the increased action preceding its death, may determine the effusion of organizable 

 matter into the surrounding soft textm-es, which will serve as a matrix or foun- 

 dation for the new shell, and be ready to take up the ossifying process so soon as 

 it is communicated from the surviving extremities of the bone. That the process 

 of reproduction may be accomplished in this way I am not prepared to deny, but 

 that it is not necessai-ily, or always so performed, will, I think, appear from the 

 following case. 



A gu-1 twelve years of age strained her ankle in the month of March 1835. 

 Inflammation followed, extending up to the knee, and attended with violent fever. 

 She was brought to the hospital, and placed under my care. Incisions were soon 

 afterwards made to evacuate a large collection of matter which had formed in the 

 leg. And the bone being found dead, while the patient's strength was rapidly 

 giving way, I amputated the limb above the knee five weeks after the injury had 

 been received. The girl recovered, and is now well. In examining the limb to 

 ascertain the extent to which the bone had died, I found that it was partially sm-- 

 rounded by the commencement of a new one. This sheU had already acquired 

 considerable firmness at some parts, but was not equally thick throughout, and 

 did not seem fixed to the ends of the old shaft. This observation led to a very 

 careful dissection of the parts concerned ; and they are now before the Society. 

 It wiU be seen that the tibia had died very neai-ly from end to end, and that the 

 new shell inclosing it has been formed in the periosteum. The new osseous sub- 

 stance may be observed at some parts in the form of small distinct scales. At 

 other parts it looked as if it had originally consisted of separate portions, and 

 been composed by their union. The periosteimi connecting these portions to each 

 other and to the extremities of the bone was not thickened beyond its natural 



VOL. XIV. PART I. X 



