TONGUE AND TEETH. 125 



The pulp This fills the cavity of the tooth within the dentine. 

 It consists of a connective tissue matrix, stellate and spindle cells, 

 round cells, and odontoblasts. The outer surface of the pulp is 

 covered with a layer of odontoblasts. Most of the cells beneath the 

 odontoblasts are stellate and spindle-shaped. The protoplasmic 

 processes of the odontoblasts, which extend into the dentinal tubules, 

 are called the fibres of Tomes. The odontoblasts are directly con- 

 cerned 'in the manufacture of dentine. 



Laboratory exercise No. 39. The teeth. Decalcify in dilute nitric 

 acid, harden in alcohol, embed in celloidin, and stain with kaematoxylin. 

 Examine a longitudinal section and demonstrate as far as possible the 

 cementum with its lamellae, lacuna?, cement corpuscles, and canaliculi; 

 also the dentine, exhibiting dentinal tubules, sheath of Neumann, den- 

 tinal fibrils, and inter-globular spaces; also the enamel, showing the 

 enamel prisms, matrix, and membrane of Nasmyth. Drawings. The 

 demonstrations of enamel must be made from dry sections, as acids 

 completely dissolve this structure. 



MEMORANDA. 



