IS 



further on, Professor Owen says " the inflected surface of the 

 tooth can be exposed to no other pressure than that of the 

 turgescent duct with which it is in contact." Now, accord- 

 ing to my observation, the poison duct ends at the bottom of 

 the mucous envelope of the tooth and between its orifice 

 and the basal orifica of the tooth there is no continuity ; 

 the two orifices are in apposition and, at the moment of a 

 bite, the saliva, having no other exit, passes through the 

 fang-canal. A continuous canal could not' exist when we 

 consider that it would be broken at the first shedding of the 

 fang and there is no ground for supposing any peculiar 

 reparative powers inherent in this duct. No explanation on 

 this point is given in Professor Owen's account of the 

 development of the fang. 



" In the posterior part of the large mucous sheath of the 

 poison-fang, the successors of this tooth are always to be 

 found in different stages of development ; the pulp is at 

 first a simple papilla and when it has sunk into the gum, 

 the succeeding portion presents a depression along its 

 inferior surface, as it lies horizontally, with the apex 

 directed backward ; the capsule adheres to this inflected 

 surface of the pulp and the base of the groove of the loose 

 growing poison-fang is brought into the same relation with 

 the duct of the poison-gland as the displaced fang which has 

 .been severed from the duct." This description of the growth 

 of the fang is perfectly correct. 



I may add that the inflected part of the capsule lining 

 the cavity of the poison-fang appears to play a great part in 

 its nutrition ; while the pulp-cavity becomes obsolete (or 

 nearly so) from the apex backwards as fast as the fang grows, 

 the capsule remains vascular until the fang is nearly perfect. 

 The more highly developed the fang, the greater this 

 nutritive function of the capsule appears to be. Thus, in the 

 cobra, the pulp-cavity is visible for more than half-way 



