164 THE VITAL FUNCTIONS. 



the pressure of the tooth, at the moment it 

 inflicts the wound, and conducted along a canal, 

 opening near the extremity of the tooth. Each 

 fang is lodged in a strong bony socket, and is, 

 by the intervention of a connecting bone, pressed 

 forwards whenever the jaw is opened sufficiently 

 wide ; and the fang is thus made to assume an 

 erect position. As these sharp teeth are very 

 liable to accidents, others are ready to supply 

 their places when wanted : for which purpose 

 there are commonly provided two or three half- 

 grown fangs, which are connected only by soft 

 parts with the jaw, and are successively moved 

 forwards into the socket to replace those that 

 were lost.* 



The tube through which the poison flows is 

 formed by the folding in of the edges of a deep 

 longitudinal groove, extending along the greater 

 part of the tooth ; an interval being left between 

 these edges, both at the base and extremity of 

 the fang, by which means there remain apertures 

 at both ends for the passage of the fluid poison. 

 This structure was discovered by Mr. T. Smith 

 in the Coluber naia, or Cobra de Capello;-\ and 

 is shown in Fig. 285, which represents the full 

 grown tooth, where the slight furrow, indicating 

 the junction of the two sides of the original 

 groove, may be plainly seen; as also the two 



* Home, Lectures, &c. I. 333. 



t Philosophical Transactions, 1818, p. 471. 



