NUTRITION OF BONE. XI 5 



uniformly filled with calcareous salts, so uniformly indeed, 

 that no interval can be perceived between the indivi- 

 dual calcareous particles. Though some few writers 

 have assumed that little granules can be distinguished in 

 it, this is an error. The only differentiation which can 

 be seen is caused by the prolongation into the "basis-sub- 

 stance of the canaliculi, which all ultimately lead back to 

 the bodies of the bone-cells (bone-corpuscles) and in 

 their turn give out branches. The peripheral extremi- 

 ties of these little branches or processes extend right up 

 to the surface of the vascular (medullary) canal. They 

 are therefore inserted exactly where the membrane of 

 the vessel begins (Fig. 35), for they can be distinctly 

 perceived as very minute orifices upon the wall of the 

 canal. Now since the different bone-corpuscles are in 

 their turn distinctly connected with one another, means 

 are afforded by which a certain quantity of juice taken 

 up from the surface of the vascular canal is not diffused 

 throughout the whole mass of tissue, but confined to 

 these delicate, continuous, and specially provided chan- 

 nels, and forced to move onwards in canals which are 

 inaccessible to injections from the vessel. For a time it 

 was believed that the canaliculi could be injected from 

 the vessel, but this is only possible when the vascular 

 canal has become empty by maceration. 



This is a condition precisely similar to what we 

 observe in the teeth, in which the canaliculi can be in- 

 jected from the pulp-cavity when empty. If a solution 

 of carmine be injected into this cavity, the dental canali- 

 culi are displayed in the form of numerous tubules run- 

 ning up to the surface side by side in a radiated manner. 

 The substance of the teeth also forms a tolerably broad 

 layer of non-vascular material. Vessels are found no- 

 where but in the pulp -cavity, in proceeding from which 

 outwards we find nothing but the proper substance of 



