THE DENTAL TISSUES. 83 



blood-vessel, the remains of which may be found even in 

 a dried section. But in human dentine vascular canals do 

 not often occur, and when they do, are to be regarded as 

 decided abnormalities. 



The accompanying figure, representing a canal of large 



size, was drawn from a specimen shown to me at the Cam- 

 bridge (Massachusetts) Museum by Dr. Andrews. 



In some mammalian teeth these vascular canals are 

 disposed with regularity, running out in loops from the 

 pulp cavity, and lying, for a considerable part of their course,, 

 at right angles to the dentinal tubes. 



In the Manatee for example the dentinal tubes radiate 

 out with perfect regularity from the central pulp chamber^ 

 and, so to speak, take no notice of the vascular canals, 



(!) Vascular canal in dentine. From a human tooth. 



G 2 



