HISTOLOGY. 93 



cells, the cuticula dentis. The enamel substance is ar- 

 ranged in columns or prisms called enamel prisms. 

 They are stuck together with a substance more dense 

 than themselves, called enamel-cement. The lines of 

 Retzius are parallel lines running from the dentine to 

 the cuticula dentis in the enamel. They represent the 

 periodic deposition of the salts of lime in the enamel. 



THE DENTINE. 



The dentine is the tissue between the enamel and the 

 pulp-cavity. It is composed of little tubes about two 

 and one-half microns in diameter. They are surround- 

 ed by the membrane of Newmann. In their course they 

 take an S-shaped direction, giving rise to the lines of 

 Schrager. Peculiarly, irregularly branched spaces are 

 seen in the dentine, called interglobular spaces. They 

 represent the uncalcified spaces in the dentine. 



The cementum is located on the tooth from the 

 crown downward, and is composed of bone plates hav- 

 ing no Haversian canals as a rule. The peculiarity 

 of the cementum is, it has a large number of Sharpey's 

 fibers, which are abundant in those arears where noe 

 bone corpuscles are found. They are found where the 

 bone has not calcified. Bohm and Davidoff. 



The pulp cavity is the cavity found in the central 

 portion of the tooth, and contains the pulp. It is very 



