GASSERIAN GANGLION: ALBINO RAT 



259 



the eruption of the mcisors occurs. Again, at about twenty 

 days, the growth of the gangUon cells, the nuclei, and the nerves 

 reach the end of their first phase, coinciding with the end of the 

 first phase of the growth of the incisors. 



The period at which the third molar erupts corresponds to 

 the period of nearly the full size of the nucleus, i.e., about thirty- 

 five days. We notice, moreover, that the period at which the 

 cell body, nucleus, and the fiber reach nearly the maximum is 

 ninety days, but the extra alveolar length of the incisors attains 

 nearly its maximum a trifle later — 105 days^ — after which it in- 

 creases slowly. Thus the fuller growth of the nerve elements 



TABLE 17 



Measurements on the incisor teeth in millimeters, on age 



Upper incisor total length 



Upper incisor extra alveolar 

 length 



Lower incisor total length 



Lower incisor extra alveolar 

 length 



AGE IN DATS 



2.3 



7.9 



Eruption 

 8-10 days 

 3.0 I 11.0 



Eruption 

 8-10 days 



300 



26.2 



9.3 



31.3 



12.4 



seems to be slightly in advance of that of the dental mechanism, 

 yet in general there is a fairly good correlation between them. 



ON THE RELATION BETWEN THE GROWTH OF THE GANGLION 

 CELLS AND THE NERVE FIBERS AND THAT OF THE CRANIUM 



Recently Donaldson ('19) studied the growth of the entire 

 skeleton, as well as its several parts, in the albino rat. So far 

 as his results on the cranium are concerned, the rate of growth 

 with respect to age coincides very well with the growth rate of 

 the ganglion cells and the fibers of the fifth nerve. 



For instance, the rapid growing period of the cranium continues 

 up to about twenty days and the next period of the slower growth 



