PHYSIOLOGICAL STUDIES OF GUSTATORY MECHANISMS 239 



in paraffin and sectioned transversely at 6//. The sections were stained 

 using the Wolters modification of the Weigert-Pal technique (Romeis, 

 1937). 



HORSE 



Fig. 4. Gross dissection left mandibular and left lingual nerves in the horse. 

 For legend see Fig. I . 



The number and diameter of the myelinated fibers in each nerve were 

 determined by measuring and counting the fibers as seen in a photomicro- 

 graph enlarged 750 times. It was necessary to make composite photo- 

 graphs of the larger nerves (Figs. 6 and 7). The equipment used in deter- 

 mining the diameter of each fiber and counting the fibers is illustrated in 

 Fig. 5. The gauge was prepared by etching a series of circles on clear 

 Plexiglass. The smallest circle was a 750 times enlargement of a circle 

 having a 2fc diameter. Additional circles were made, each of which com- 

 pared to circles enlarged l/t in diameter. The largest circle corresponded 

 to the enlargement of a circle 22// in diameter. The diameter of each 

 myelinated fiber was measured and the fiber counted in the following 

 manner. The smallest circle of the gauge was placed over the photo- 

 graphic enlargement of the fibers. If the outer edge of the fiber was equal 

 to or smaller than the etched circle, the fiber was counted and marked by 

 puncturing the photograph using a needle inserted through a hole in the 



