DR. Til. NEUMANN. 103 



perfectly developed on each side ; but on a more careful 

 inspection one may discover two or more reserve teeth of 

 smaller size and less developed behind the principal one 

 which sit very loosely on the jaw-bones and are destined 

 to move forward and to serve as substitutes in case the 

 first should be lost. Consequently, the one nearest in 

 front is the most highly developed. 



These teeth are distinguished always by their great 

 length and their peculiar curved shape. They are as hard 

 as glass and brittle, but possess an extremely fine point 

 so that they penetrate easily even things of comparative 

 resistance, as leather, while, on the other hand, they sli]3 

 off hard ones or even break into small pieces if the blow of 

 the snake is a very violent one. If one is lost, the one 

 following behind will take its place. With some groups 

 such a change is going on with a certain regularity with- 

 out any reason or provocation from outside, perhaps 

 once a year or oftener. 



The development of such poison-fangs proceeds with 

 marvelous rapidity ; investigators have found out that 

 embryos which had apparently been born within five 

 or six days had none at all yet, while others only 

 one or two days before their leaving the egg had them in 

 perfect working order. Each tooth is in its first state a 

 sheet only with edges rolled up so that it shows the 

 groove, beyond which the development does not go in 

 certain groups, in the Proteroglypha, which take their 

 name from this very circumstance. 



In the Solenoglypha the sides of this groove approach 

 each other and finally grow together, thus forming a 

 tube which is entirely closed and forms a higher state of 

 development. 



In either case the canal or the tube is connected with 

 the duct of the "poison-gland." This is a gland, situated 

 under and behind the eye, secreting the poisonous fluid 

 which renders the bites of these snakes dangerous or 



59 



