HISTOLOGY OF SENSORY GANGLIA OF BIRDS 261 



nerve cells. The cells of the ganglion are irregularly grouped as 

 ■ in the spinal and tenth ganglia. They are. more crowded at the 

 periphery than at the center. In the center the bundles of nerve 

 processes separate the cells into groups of varying numbers, so 

 arranged that the long axes of the groups are parallel to the long 

 axes of the ganglion. The cells are more numerous at the proxi- 

 mal than at the distal end of the ganglion, this being a reversal 

 of the condition found in the ganglion of the tenth nerve. The 

 sensory cells range in size from those with the major axes between 

 25 and 70 m, and minor diameters between 15 and 40 m- The 

 nuclei are uniformly regular in shape, varying from round to 

 elliptical. The major diameter of the nuclei is between 8 and 

 14^1 and the minor diameter is between 6 and 11 ^i. A single 

 centrally placed nucleolus was observed in each nucleus. 



Good examples of perinuclear network were abundant in the 

 cells of the Gasserian ganglion. The meshes of the network are 

 finer near the nucleus, and, since these fibrillae stain deeper than 

 the remaining substance of the cell, the close meshed perinuclear 

 network appeared as a dark ring around the nucleus. 



A notable coiling of the central axis, not involving the sheath, 

 was observed in a Gasserian ganglion counterstained with Dela- 

 field's haematoxylin. Fibers of this nature were in tracts free 

 from cells and also in parts of the ganglion containing cells. 

 Figure 11 shows this condition; the two sections of the picture 

 represent a single process, the ends a and h being continuous. 

 A reexamination of other Gasserian ganglia, not counterstained, 

 showed the presence of many fibers having similar convolutions. 

 It would appear that this condition is not uncommon, though I 

 have found no recognition of it in the literature. 



The Gasserian ganglion of the old hen presents histological 

 features that differ widely from those observed in the younger 

 birds (see also under Vagus). The regularity of outline in the 

 cells, so marked in the younger birds, is not characteristic of 

 the old hen. The outline of the cells of the old bird is frequentlj^ 

 quite irregular and the surface presents numerous rugosities. 



Vacuoles, varying in number from one to six, are also of fre- 

 quent occurrence in the cells of the Gasserian of the old hen. 



