GASSERIAN GANGLION I ALBINO RAT 245 



We here find (table 9) that the volume of the ganglion cells 

 of the gasserian ganglion increases at the approximately same 

 rate as the area of the surface of the head during the period in 

 which the gasserian cells are growing. There is, therefore, a 

 similarity in the behavior of these specialized cells while they 

 are still growing to those in a typical spinal ganglion. 



THE NERVE FIBERS 



The nerve fibers from the first (ophthalmic) , the second (maxil- 

 lary), the third (mandibular), branches and the root of the Vth 

 nerve were studied on thirty-nine normal albino rats. The body 

 weights in this series ranged from 6.7 grams to 320 grams and 

 the ages from four days to 485 days. The original data represent 

 the averages of the ten largest fibers arranged according to their 

 ages. From the original table thus drawn up the author has 

 made the condensed table 10. From the condensed table the 

 oldest rat was omitted, thus leaving thirty-eight animals, and 

 the data for these are presented in nineteen groups, each group 

 representing two rats of like age. 



Table 10 gives the average values from 4 to 378 days in 

 nineteen age groups. The same data as given in table 10 have 

 been arranged also according to body weight, but the latter 

 shows almost the same relations as table 10, and is therefore not 

 printed. 



Chart 4 shows graphically the data given in table 10. The 

 ordinates represent the average diameter of the fibers and the 

 abscissas the ages. 



THE DIAMETER OF THE NERVE FIBERS 



Among four different sets of nerve fibers, table 10 shows that 

 those fibers belonging to the first (ophthalmic) branch give the 

 smallest average diameters which measure 7.6 ju and the axis 

 cylinders 5.4 ^u. The largest average diameters are given by the 

 fibers belonging to the fifth nerve root, and these measure 11 m 

 and the axis cylinders 7.8 //. 



