GASSERIAN GANGLION: ALBINO RAT 257 



are not sufficiently extensive. However, I can distinguish three 

 types of ganghon cells, as was noted by Hatai, for the spinal 

 ganglion cell in the albino rat. 



As shown in plate 1, the largest cells in all the four age groups 

 show the following arrangements of the stainable substance. 



A. The cells with large, coarse, stainable masses which lie 

 throughout the cell body without showing a regular or constant 

 arrangement (figs. 2, 5, 8, 11). 



B. The cells with large, coarse, stainable masses only at the 

 periphery. Smaller masses fill up the remaining part (figs. 3, 

 6,9,12). 



C. The cells with large, coarse, stainable masses which lie 

 throughout the cell body, showing a regular, concentric arrange- 

 ment (figs. 1, 4, 7, 10). 



In all these cells clear spaces around the nucleus and at the 

 extreme periphery of the cell body are distinctly visible. 



The small cells and those intermediate in size show at each 

 age a somethat similar distribution of the stainable substance, 

 but tend to differ from the largest cells by having the clear zones 

 less sharply marked and by a tendencj^ to shrink, which is most 

 marked in those of smallest size. 



Thus the morphological characters of the cells which compose 

 the gasserian ganglion are similar to those shown by the cells 

 of the spinal ganglion. 



ON THE RELATIONS BETWEEN THE GROWTH OF THE GANGLION 

 CELLS AND THE NERVE FIBERS AND THAT OF THE TEETH 



Since the fifth nerve supplies its branches not only to both 

 maxillaries, but also to the teeth, it is conceivable that the cells 

 and fibers of the gasserian ganglia might be correlated in their 

 growth with that of the dental mechanism. I have endeavored 

 to determine whether or not such a relation exists. 



Addison and Appleton ('15, pp. 91-93) studied the growth of 

 the incisors of the albino rat and found that "In animals one day 

 old the upper and lower incisor teeth measure 2.3 and 3 mm., 

 respectively. At 8 to 10 days these teeth erupt, and at 10 days 

 measure 7 and 11 mm. respectively. This period is therefore 

 characterized by the rapid elongation of the teeth. The process 



