328 SPECIAL HISTOLOGY. 



stance, as has already been said, in respect of its fibres and cells, 

 entirely corresponds with the ossific blastema beneath the periosteum, 

 and, in a certain degree, is merely an originally unossified remainder of 

 it. These conditions are easily observed in young bones, in which, the 

 periosteal layers, before they have undergone any resolution, are 

 rendered more and more compact by these new, secondary lamellae; but 

 even at a later period a more or less ossified blastema (always without 

 calcareous granules) may very frequently be perceived on the walls of 

 the canals in question. Whilst the vascular canals are thus, on the one 

 side, undergoing contraction by the deposition of these secondary layers, 

 which, just as in the periosteum itself, appear laminated, either be- 

 cause the ossific blastema itself is so constructed, or because the depo- 

 sition of bone takes place with periodical pauses, they afterwards 

 widen, or at least some of them, by absorption, as for instance, the 

 canales nutritii, the great vascular openings in the apophyses, &c. ; and 

 the compact substance, as has been already remarked, is also, in many 

 places partially, and in some even entirely, absorbed. 



In what way the bone increases in thickness in the situations where 

 tendons and ligaments, 'without the intervention of periosteum, are 

 directly implanted into it has not yet been made out. From the cir- 

 cumstance, that in the adult, in many of these situations, true cartilage- 

 cells occur among the tendinous fibres, and also, that their passage into 

 bone-cells may very clearly be observed, it might perhaps be concluded 

 that a similar process may take place at an earlier period also. In fact, 

 I have seen, even in young individuals, at the points of insertion of 

 many tendons and ligaments (tendo Achillis, lig. calcaneo-cuboideum, 

 aponeurosis plantaris, $c.) into the bone, cartilage-cells, and their meta- 

 morphosis into bone-cells. Very frequently, also, tendons and ligaments 

 are attached to portions of the bone which remain long in the cartilagi- 

 nous condition, epiphyses, tuberositas calcanei, c., and the growth of 

 these parts, of course, is simply to be referred to the cartilage. 



The formation of bone on the inner aspect of the periosteum is a fact 

 long well known, although it has, hitherto, generally been thought, that 

 in this situation also, it was preceded by a thin cartilaginous layer, until 

 the contrary was shown by Sharpey and myself. Since the discovery by 

 Duhamel ("Me'moires de 1'Academie de Paris," 1742, p. 384, and 1743, 

 p. 138), that the bones of animals fed upon madder are colored red, a 

 great number of experiments have been made with that substance, espe- 

 cially by Flourens, in growing animals ; it being at first believed, that 

 it only colored those parts of the bones which were formed after its 

 administration. This method, however, has lost a good deal of its value 

 since it has been shown by Rutherford (in " Robert! Blake, Hiberni, 

 Dissert, inaugural, med. de dentium forrnatione et structura, in homine 



