GASSEEIAN GANGLION: ALBINO RAT 2G5 



is about the same in the younger and in the older rats. The 

 amount of the difference is, however, small. 



4. So far as the diameters of the cell body, the nucleus, and 

 the fibers are concerned, the difference between those from the 

 left and those from the right side is negligible. 



5. The ratios between the volumes of the cytoplasm aitd the 

 volumes of the nuclei increase with increasing size (age) of the 

 ganglion cells, and the largest cells give a ratio over twice as 

 large as that found in the smallest. 



6. At about twenty days after birth the cell body and the 

 nucleus show almost the same appearance as that in the adult 

 rat. After twenty days both increase in size, and there is also 

 an increase in the cjuantity of the Nissl substance, but the other 

 changes of a morphological character are very slight. 



7. The diameter of the fibers is least in the first branch (oph- 

 thalmic) and largest in the fifth nerve root, while the fibers of 

 the second (maxillary) and the third (mandibular) branches are 

 similar and give intermediate values. 



8. The relative area of the axis cylinder to that of the entire 

 fiber increases slightly with age, and approximates the one-to- 

 one relation in the nerve fibers of the adult rat. 



9. The volume of the ganglion cells increases at the same rate 

 as the area of the head surface in the j^ounger animals, before 

 eighty days of age; but after this age the growth of the neurons 

 becomes very slow, while the growth of the head continues. 



10. After about eighteen days of age the areas of the axis 

 cylinders of the fifth nerve increase at about the same rate as 

 the area of the head; previous to this age the growth in the area 

 of the head has been the more rapid. 



11. The ratios given by the diameters of the ganglion cells 

 to the diameters of the nerve fibers decrease with increasing body 

 weight. The decrease of the ratios after puberty is due to a 

 longer continued growth in diameter of the fiber as compared 

 with that of the ganglion cells. 



12. The neurons in the gasserian ganglion are larger, have a 

 higher nucleus-plasma ratio, and mature earlier than do those 

 in the ganglion of the seventh cervical nerve. The fibers from 



JHE JOUBNAJ, QF CQMPARATIVE NEUROLOGY, VOL. 32, NO. 2 



