72 NORMAL HISTOLOGY, 



lacunae in the bone proper and note their arrangement; also find Haver- 

 sian canals and make out, if you can, Haversian systems. Examine 

 the marrow and demonstrate marrow cells and osteoclasts. Prepared 

 specimens of dry bone should be examined to demonstrate lacunae and 

 canaliculi. The bone of a foetus may be prepared for the study of bone 

 development. The preparations need not be preserved unless especially 

 good. What is the average diameter of the canaliculi? Drawings. 



X. DENTINE. 



Dentine is one of the connective tissues, being derived from the 

 mesoderm. It is commonly known as ivory and is found in the 

 teeth. It differs from bone in composition and structure. Its inti- 

 mate structure will be given in the chapter on the teeth. 



MEMORANDA. 



