466 ANATOMICAL AND PATHOLOGICAL OBSERVATIONS. 



impossible to separate the periosteum from a dog's radius 

 without removing along with it minute longitudinal, fila- 

 mentary, or ribbon-shaped portions of the surface of the bone ; 

 more particularly, as may be conceived, when performed in 

 the manner which under the circumstances would be adopted, 

 by slitting it up in front, and detaching it transversely before 

 separating the portion of bone. It remains to be proved that 

 it is not from these minute shreds of bone that the regenerated 

 portion of the shaft has derived its origin.* 



In the other part of the experiment, in which the 

 periosteum as weU as the bone was removed, it was not to be 

 expected that complete regeneration should have taken place, 

 inasmuch as the bounding or Kmiting membrane of the organ 

 had been removed, and the surrounding textures were allowed 

 to collapse and unite. Even under these unfavourable cir- 

 cumstances, the cut extremities of the bone had lengthened 

 themselves out in a conical form. 



The two subsequent experiments, by the insertion of tin 

 plates, though highly ingenious, differ in no essential particular 

 from the first, and are liable to the same objections. If a 

 section had been made through the denuded shafts, new bone 

 would have been found deposited in their interior, just as it 

 had been at the cut extremities in the first experiments. 



The careful examination of numerous bones, the shafts of 

 which had died, and were in progress of replacement by a 

 substitute in the form of a shell, has satisfied me that in no 

 instance do we ever see a new shaft, without at the same time 

 observing portions of the old shaft ulcerated to a greater or 

 less extent — the ulcerated portions invariably corresponding 

 in the early stages to the scales of new bone in the periosteum. 

 Whenever the old shaft is entire, its periosteal surface pre- 

 senting the natural appearance of a macerated bone, the part 

 corresponding to this in the new shaft is formed of bone which 



* Baly. Note in his Translation of Miiller's Physiology, page 471. 



