ERUPTION OF THE PERMANENT TEETH 151 



Magitot (37) called attention to the differences in the decay of 

 the teeth in Normandy and Brittany, and attributed the difference 

 to the type of people in the two compartments of France. In 

 Brittany are the Celts or Gauls, who are small, with dark hair 

 and eyes, broad head, and with good teeth; in Normandy are the 

 Belgians or Kymries, who are tall, with fair hair and eyes, long 

 head, and with bad teeth. The color of hair and eyes seems to be 

 incidental, because in those I examined with bad teeth and of 

 hyper-onto-morph form, the color of hair and eyes was of all 

 shades. In southern Europe the long head has dark hair and 

 eyes and in northern Europe fair hair and eyes, and in central 

 Europe the broad head has dark hair and eyes and in eastern 

 Europe the same form has fair hair and eyes. The morphologic 

 type is independent of pigmentation and I believe the time of 

 eruption of the permanent teeth and the extent of their decay 

 are due to inherent differences in the morphologic type of the 

 individual. 



The teeth of the hyper- form are undergoing retrograde meta- 

 morphosis because they appear early and decay early. It is 

 believed that the third molar in man is undergoing retrograde 

 metamorphosis more rapidly than the other teeth and there are 

 indications that the canines are also undergoing rapid retrograde 

 metamorphosis, because the canines appear late and the third 

 molars sometimes do not appear at all. It is strange to say that 

 the teeth of the hyper- are undergoing retrograde metamorphosis 

 because they appear early and decay early and the canines and 

 molars are undergoing retrograde metamorphosis because they 

 appear late or not at all, yet such is the inference. In the case of 

 the hyper- there is rapid differentiation with early decay and in 

 the canines and premolars retardation or failure to appear 

 through backwardness. Retrograde metamorphosis, as in the 

 human ear, seems to come about with precocity, involution prob- 

 ably occurring earlier and earlier with each succeeding generation, 

 therefore the hyper- is a very much involved form. Involution 

 in the teeth may occur in the same way until crowding causes 

 the third molars and canines to appear late and finally to fail to 

 appear. There may also be more than one method of evolution. 



