GUSTATORY ORGANS OF AMPHIBIA. 



19 



The peripheric process is in general furcate, and O021 to 

 0'030 of a millimeter long. Its ends reach the free surface of 

 the epithelium. As in a fork, a handle and prongs may be dis- 

 tinguished. The handle is cylindrical, upon the average 0'0015 

 0'002 of a millimeter thick, and at most only 0*008 of a milli- 

 meter long, or it may even altogether fail. The shorter it is 

 so much the longer are the fork prongs proceeding from it, and 



Fig. 278. 



I ! 



Fig. 278. Isolated fork-cells from the Frog (Rana temporaria) . 

 Magnified 600 diameters. 



vice versa. The handle divides into two, .or more rarely into 

 three, prongs, which sometimes again form secondary forks. 

 Sometimes a third prong arises laterally from the handle. The 

 apices of all the prongs lie in one plane, namely, the surface of 

 the epithelium. The prongs are cylindrical rods of at most 

 O'OOl of a millimeter in thickness, and closely resemble pale 

 nerve fibres in their physical and chemical relations. 



A single thick cylindrical process, having an average diameter 

 of O'OOl 5 of a millimeter (or more rarely two or three more 

 slender ones), arises from the centric pole of each fork-cell, ancf 

 after running for at most a distance of 0'025 of a millimeter, 

 and usually not more than 0'006 of a millimeter from the pole, 

 divides into two branches. From these branches, smaller very 

 delicate branches proceed, and again subdivide, which present 

 the same appearance as the pale nerve fibres spreading over 

 the surface of the nerve cushion, and are very probably con- 

 tinuous with them. 



Mutilated fork-cells appear to have been seen both by Billroth 



c 2 



