TRANSPLANTATION OF PERIOSTEUM. 153 



bioplasm, while nothing of the kind exists in the case 

 of the canaliculi. The notion of cells shooting-out 

 processes which meet those of other cells is a most 

 fanciful one, and totally unsupported by observation. 

 The idea as applied to the bone- cells is purely hypo- 

 thetical, and would never have been advanced had it 

 not been first assumed that the lacuna with its ca- 

 naliculi was a stellate cell. Such an assumption 

 necessarily required new assumptions to support it, 

 and so the unfortunate hypothesis of " boring pro- 

 cesses " had to be invented. 



212. Of the changes beneath the periosteum and 

 medullary membrane. The outer layers of the pe- 

 riosteum exhibit a simply fibrous structure, but its 

 deeper portion, which is continuous with the bone 

 tissue, has a totally different anatomical arrangement. 

 Here are seen a number of elementary parts of un- 

 ossified bone tissue, each consisting of an oval mass 

 of bioplasm invested by a soft formed material. The 

 deeper layer of the periosteum of a young animal is 

 the seat of the formation not only of new bone but of 

 complete Haversian systems. The elementary parts 

 multiply, and the capillary vessels are gradually en- 

 closed by the growth of tissue, which at length un- 

 dergoes ossification. This process has been fully de- 

 scribed by Messrs. Tomes and De Morgan. 



213. Transplantation of periosteum. It has been 

 shown by M. Oilier, of Lyons,* that if portions of 

 the periosteum be transplanted to various parts of the 

 organism, bony tissue will be formed in the new 

 situation. This process is due to the growth and 

 development of the masses of bioplasm which exist 

 in such great number at the deep surface of the 

 fibrous periosteum. These grow and multiply, and 

 produce formed material, just as if they had remained 

 in the original seat of their development a striking 



* " Journal de la Physiologie, " torn, ii., pp. 1 and 169. 



