Origin and distribution of the tractus solitarius in the guinea pig

Several years ago the writer began a series of experiments and studies on the guinea pig's brain to determine if perchance the central connections of the general visceral and gustatory systems in mammals were comparable to those found by Herrick and Johnston in fishes. In brief, Herrick's description of the gustatory system of the carp, catfish and Amblystoma may be summarized as follows: Both gustatory and general visceral sensory impulses are conducted by the VII, IX and X nerves to facial and vagal lobes of the medulla. From these primary centers two descending secondary gustatory tracts follow the spinal V tract to the region of the commissural nuclei and two ascending secondary gustatory tracts accompany the spinal V tracts to two superior secondary gustatory nuclei, situated in the isthmus, ventrally to the line