4 THE GUSTATORY ORGANS, BY TH. W. ENGELMANN. 



upper surface and the sides present low perpendicular folds, i.e., 

 folds running parallel to the axis of the papilla, with intervening 

 furrows." He also observes " that these furrows are completely 

 filled with epithelium, so that the surface of the papilla is everywhere 

 perfectly smooth, and exhibits no trace of the subjacent inequalities. 

 The epithelial layer is considerably thicker upon the upper surface 

 and that portion of the papilla which is not protected by the circular 

 wall, than upon the protected lateral portions ; but even in the former 

 situations it is far thinner than upon the remainder of the surface of the 

 tongue. The epithelium is also very thin upon the external wall of 

 the vallecula. The gustatory bulbs are situated in the thin epithelium at 

 the sides of the papilla, and indeed there usually form a zone that extends 

 from the bottom of the fossa upwards to about the level at which the 

 papilla is no longer protected by the lateral wall (Schwalbe). The 



Fig. 270. 



Fig. 270. Transverse section through a papilla circumvallata of a 

 Calf. Showing the arrangement and distribution of the gustatory 

 bulbs. Magnified 25 diameters. 



zone, like the wall, entirely encircles the papilla. If the fossa be 

 deep, as in the Sheep and Pig, the zone is broad ; if, as in the Horse, 

 it be shallow, it is narrow. In Man, however, even when the fossa is 

 deep, the upper half of the lateral wall of the papilla appears to be 

 destitute of gustatory bulbs (Schwalbe). The number of the gustatory 

 bulbs is very great, since as a rule they stand in close contiguity to 

 one another, and most so in Man, where, according to Schwalbe, they 

 are in absolute contact. Schwalbe estimated the number present in 

 one papilla of the Sheep, of moderate size, at 480 ; in one from the Ox, 

 at 1,760 ; in the Pig, which only possesses two circumvallate papilla?, 

 each has about 4,760 bulbs. This would give a total number of bulbs 

 in the Sheep, of 9,600 ; in the Ox, of 35,200 ; in the Pig, of 9,520. 

 In Man and in the Dog, according to Schwalbe, and in the Rat and 

 Rabbit, according to Loven, a few bulbs usually appear to be scattered 

 on the outer wall of the vallecula, or that which looks towards the 



