THE MODE OF REPRODUCTION AFTER DEATH, &c. 69 



accurately. I have satisfied myself, that it is impossible to se- 

 parate the periosteum from a dog's radius without removing 

 along with it minute longitudinal, filamentary, or ribbon-shaped 

 portions of the surface of the bone, more particularly, as may be 

 conceived, when performed in the manner which under the cir- 

 cumstances would be adopted, by slitting it up in front, and de- 

 taching 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 well as the bone was removed, it was not to be expected that 

 complete regeneration should have taken place, inasmuch as the 

 bounding or limiting membrane of the organ had been removed, 

 and the surrounding textures were allowed to collapse and unite. 

 Even under these unfavourable circumstances, the cut extre- 

 mities 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 sub- 

 stitute 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 periostea! surface presenting the na- 

 tural appearance of a macerated bone, the part corresponding to 

 this in the new shaft is formed of bone which is seen to be shoot- 

 ing, in the manner peculiar to this mode of regeneration, from a 

 point corresponding to an ulcerated portion of the old shaft. So 



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



