INCISORS OF FIRST DENTITION. 



15 



time the bone of the jaw increases in size, and the permanent 

 incisors form in them. 



These develop behind the deciduons teeth, and are at first 

 separated from them by a bony septum, which, however, usually 

 becomes thinned, and the permanent tooth pushes the other out, 



Fig. 6. 

 A, permrment incisor just before eruption ; 15, deciduous incisor in place. 



but sometimes they come from an independent opening and 

 the milk-tooth remains in place. 



The absorption of the bone, by pressure of the developing 

 teeth, is frequently attended by constitutional phenomena, loss of 

 appetite, sluggishness, etc., and I have seen it produce convul- 

 sions in a colt two and a half years old. 



There is an old superstition that the period of eruption of 



