THE ORGAN AND SENSE OF TASTE IN FISHES. 
249 
tricle as the fasciculus communis ( = fasc. solitaries of mammals) to terminate in the 
vagal lobe of the same side, and receives in its course the communis root of the glos- 
sopharyngeus nerve. But in siluroids and cyprinoids, where the very abundant 
terminal buds of the outer skin are all innervated from the communis loot of the 
facial nerve, the consequent increase in the size of this root has resulted in a great 
enlargement of the cephalic end of the gustatory center (vagal lobe) which appears 
on the dorsal surface of the oblongata as the facial lobe. This structure is paired in 
siluroids and was formerly called the lobus trigemini, an inadmissible term, since it 
has nothing whatever to do with the trigeminus nerve. In cyprinoids it is unpaired 
and is referred to in the older literature as the tuberculum impar. 
The cyprinoid fishes also have long been known to have terminal buds {Beefier - 
organe ) widely distributed over the outer body surface; but neither the innervation 
of these organs nor the exact composition of the cranial nerves has ever been worked 
out in any cyprinoid fish. A cursory examination of a series of sections prepared 
Fig. 3. — A projection of the cutaneous branches of the communis root of the facial nerve in Amciuruss mclas, as seen from 
the right side. The outline of the brain is indicated by the stippled area and the positions of the eye and anterior and 
posterior nostrils are indicated. The projection is reconstructed from serial sections, but is not drawn accurately to 
scale. More detailed reconstructions of the cranial nerves and lateral-line sense organs of this fish are given in the 
Journal of Comparative Neurology, vol. xi, No. 3, plates xiv and xv (Herrick, ’01). 
by the Weigert method through the entire head and body of a small gold-fish ( Caras - 
sius auratus) has convinced me that the same conditions in general prevail in the 
cyprinoids as in the siluroids. That is, the enormous size of the vagal lobes of 
cyprinoids is explained by the fact that these are the terminal centers for the vast 
numbers of nerve fibers entering the brain bv way of the ix and x nerves from the 
palatal organ, this remarkable structure being crowded over its entire extent with 
taste buds and probably Serving to filter food particles out of the mud taken into the 
mouth. 
On the other hand, the tuberculum impar, or facial lobe, receives the entire 
communis root of the facial nerve. This root receives fibers from practically all 
parts of the outer surface of the body, and we may infer b} T analogy with other 
fishes that these fibers connect with the terminal buds in these cutaneous areas, 
though we have as yet no actual demonstration of this fact. The terminal buds of 
the skin of the head are supplied mainly, as in Ameiuvus , by way of the infraorbital 
trunk. The terminal buds in the skin of the body of the gold-fish are not, however, 
