HISTOLOGY OF SENSOEY GANGLIA OF BIRDS 273 



is a little over 1 mm. in width. The cells throughout the ganglion 

 are arranged in single rows of four to thirteen separated by bundles 

 of fibers. There is no crowding of cells about the periphery as 

 was so commonly observed in the other ganglia. The predominat- 

 ing form of the cell in this ganglion is elongated. Many of them 

 were very long and slender, one measured 82 n in length and only 

 18 fj, in breadth. It, like many others, is tapering toward both 

 ends like a spindle. Of the remaining cells, the elliptical are more 

 common, a few are pear-shaped, and the rest are rounded and 

 irregular. The cell of largest volume was 30 by 63 ^ and the 

 smallest 14 by 27 /x. There was a uniform gradation in the sizes 

 from the largest to the smallest. 



The nuclei are round to elliptical and vary in major diameter 

 between 8 and 16 fj, and in minor diameter between 7 and 13 m- 

 But one nucleolus was observed in any nucleus. 



The cells are surrounded by thin capsules in which are the 

 characteristic nuclei. A rather limited space separates the cell 

 from its capsule. The processes issue in nearly all cases in a 

 direct line. A few bipolar cells were observed, one process being 

 slender and the other considerably larger. 



c. Gasserian ganglion of the domestic duck. The Gasserian 

 ganglion of the domestic duck is very large. The one measured 

 was 5 mm. long and over 2 mm. broad. The cells are slightly 

 more numerous around the periphery than in the central region. 

 Those in the body of the ganglion are separated into elongated 

 groups with one to three rows in each group and 2 or 3 to many 

 cells in each row. The larger number of cells are rounded, others 

 are elliptical, pear-shaped, and irregular. 



In major diameters the cells range between 22 and 74 n, and 

 in minor between 19 and 44 ix. The nuclei are larger than those 

 observed in the cells of other ganglia of the duck. The largest 

 measured 14 by 17 fi, and the large ones were abundant. They 

 ranged downward in size to one having a uniform diameter of 

 7 ju. The pericellular capsule and its nuclei are like those in the 

 other ganglion cells. The majority of the processes observed 

 follow a direct course on emerging from the cell. A few had initial 

 glomeruli, but no implantation cones were seen. A limited num- 



