THE VISCERA. 



201 



their root single, flat, or (rarely) slightly bifurcated. The superior are 

 stronger; the root of the second superior bicuspis is usually bifurcated. 



2. D. molares majores, the three posterior back teeth (the last called dens 

 sapientia), have a low broad crown with three or four tubercles (tri, quadri- 

 cuspidati,') and two, three, or four at one time parallel, at another diverging, 

 or hooked, curved roots ; those of the wisdom teeth are united into a single 

 root. Lent, molar, major. 



6 superior, 

 6 inferior, 



[Dental formula: 



3 ft 



4 .i 



1 1 



Incisors Canines 

 4 



E 

 * 





5 5 



Molars - =32. TRANS.] 

 55 



Elements of the teeth. 



1. Dentine, substantia ossea s. ebur, forms the principal mass and the founda- 

 tion of the teeth, is marrowless and non-vascular, formed of layers not of 

 canals, harder and more transparent than the (common) substance of the 

 bones, of which a thin layer covers the external and internal surfaces of the 

 root of the tooth. It is yellowish white, iridescent, consisting of concentric 

 layers and parallel longitudinal fibres and especially rich in Chondrin. This 

 last is "wanting in 



2. The Enamel, subst. vitrea s. corticalis, which covers the crown, is bluish 

 white, very hard (resisting the file) and heavy, presents horizontal fibres, 

 and is said to be deposited from a peculiar organ, membrana adamantina 

 (Purkinje). 



1. Subst. ossea. 



Phosphate of lime - - 61-95 



magnesia - - ]05 



Carbonate of lime - - 5-30 



Fluoride of calcium - - 2-10 



Soda and common salt - - 1-40 



Cartilage and water - - 28-00 



2. Subst. vitrea. 



Phosphate of lime - - 85-3 



Carbonate of lime - 8'0 



Phosphate of magnesia - - 1-5 



Membranes, soda and water - 0'2 



