PHYSIOLOGICAL STUDIES OF GUSTATORY MECHANISMS 243 



Some of the results of the fiber diameter distribution studies are pre- 

 presented in Figs. 9 and 10 and Table 1. Three nerves from two or three 

 animals of each species were studied. In general, the greater the body mass 

 of a species, the more numerous are the myelinated fibers in the chorda 

 tympani nerve (Table 1). These results are in agreement with similar 



/ 





P 



^.m 



/ 



cow 



HORSE 



Fig. 8. Photomicrographs of selected cross sections from serially sectioned 



chorda tympani nerves of the cow and the horse. Arrows point to perineural 



trabeculae. Note differences in the number of fasciculi at the different levels. 



Distance between the first and last sections illustrated is within 500/6 



results published by Quilliam (1956) in studies of the sural nerve and the 

 nerve to the medial head of the gastrocnemius muscle in several species of 

 animals. Species with greater body mass have more myelinated chorda 

 tympani fibers of larger diameter (Fig. 9). A notable exception to this 

 generalization is in dogs. About 40 per cent of the fibers in the chorda 

 tympani nerves of dogs are less than 6fi in diameter. Goats, pigs, and sheep, 

 each with greater body mass than the dog, have comparatively more fibers 



