STRUCTURE OF HUMAN TOOTH 167 



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tion it is to separate them and cast them 

 out of the body. 



(5) l To warm and moisten all parts of the 

 body.' * 



The illustration (Fig. 51) is taken from a 

 photo-micrograph showing human blood cor- 

 puscles amplified to 1,000 diameters. The 

 exposure required was 25 minutes ; the focal 

 length was 25 inches ; the one-sixth objective 

 and an eyepiece of 1 diameters were used. 



Section of Human Tooth. 



The vertical section of the human tooth, 

 roughly speaking, shows the enamel on the 

 crown, the dentine, the neck, the fangs, the 

 pulp cavity, and the Crusta petrosa, or cement 

 which surrounds the fangs. 



The dentine constitutes the greater portion 

 of the substance or mass of the tooth; it 

 corresponds with the ivory in the tusks of 

 other creatures, and is whitish and of a silky 



* Kirkes, Handbook of Physiology. Morrant Baker's 

 Edition. (John Murray.) 



