22 CHEMICAL COMPOSITION OF THE BONES. 



fluid mercury be used it will make its way through the vascular 

 foramina to the external surface. — 



The existence of absorbent vessels, and even of nerves, in 

 bones, is equally certain with that of the blood-vessels, but they 

 are not easily demonstrated. 



[The French anatomists have occasionally traced branches 

 of the fifth pair of nerves going along with the nutritious arte- 

 ries into some of the bones ; but as yet no other nerves have 

 been seen by them. M. Portal speaks in familiar terms of the 

 existence of both nerves and lymphatics in the bones, as if he 

 had often noticed them ; he, however, has omitted to inform 

 us of the source, from which the former come.] In the sound 

 state bones have no sensibility, but pain is often felt in them 

 when diseased. 



— We cannot doubt the existence of the absorbent vessels in 

 bones, since Cruikshank and Soemmering, afSrm it from their 

 own observation, and from their own injections. Breschet, ha? 

 observed it many times, and Bonamy, in making a mercurial 

 injection of the inferior extremities, " was able to follow them 

 for some time in the interior of the osseous tissue." 

 — They possess (according to Bichat,) a certain degree of ex- 

 tensibility and retractility, which is developed so slowly as to 

 be almost insensible in its progress. These properties are de- 

 monstrated in the expansion of the bones of the face, from 

 tumors of the antrum, and in the retraction of the sockets of 

 the teeth, after the loss or removal of the latter. — 



Modern chemistry has ascertained that the earthy matter of 

 bones is principally a phosphate of lime ; carbonate of lime, in 

 a smaller quantity, is also found in them. These earthy sub- 

 stances compose near one-half of the weight of bones, and a 

 large proportion of the remainder appears to be gelatinous and 

 cartilaginous matter. 



— The chemical composition of bones will be found to vary, 

 in the different ages of life, and in some measure according to 

 the individual bones selected for investigation ; the inner com- 

 pact plate or vitreous table of the cranial bones, and the petrous 

 portion of the temporal, possessing a greater relative amount 



