64 Bulletin of Laboratories of Denison University \y»^- xiii 



be correlated with the fact that its gustatory impressions come 

 mainly from the outer skin and so give rise to more general 

 body movements, such as turning and seizing, rather than to 

 movements of the intrinsic musculature of the palatal organ, 

 for which the root fibers of the motor layer of the vagal lobe are 

 mainly designed. The substantia reticularis is known to be 

 related not only to the cranial motor nuclei of the branchial or 

 visceral type, as mentioned above, but also to contain cells 

 whose neurites reach the fasciculus longitudinalis medialis and 

 other paths with somatic motor connections (see Cajal, '96, 

 p. 129 and Fig. 16), so that we have here a very direct mechan- 

 ism for producing the movement of eye-muscles and trunk-mus- 

 cles necessary for locating and approaching a sapid substance 

 which has been perceived by contact with taste buds of the 

 outer skin. 



2. Secondary Gnstatoiy Tracts. 



The secondary connections of the vagal, glossopharyngeal 

 and facial lobes are of two general types : — (i) short paths, by 

 way of the intrinsic secondary neurones or of collaterals of the 

 neurites of the chief cells, directly to the motor layer of the 

 vagal lobe and to the substantia reticularis of the oblongata ; 

 and (2) long paths to regions above and below the oblongata, 

 arising from the chief gustatory neurones. The connections of 

 the first type are diffuse and largely unmeduUated ; they have 

 been briefly described above. The connections of the second 

 type are compact well defined tracts of meduUated fibers which 

 will be termed the ascending and descending secondary gusta- 

 tory tracts. 



A word of further explanation may be necessary here in 

 justification of the i&rm gustatory as applied to these tracts. We 

 have seen above that the communis roots of the VII, IX and X 

 nerves in fishes generally contain fibers from taste buds in the 

 mucous membrane of the mouth or in the outer skin and also 

 fibers which end peripherally by free arborizations unrelated to 

 any specialized sense organs — undifferentiated visceral endings. 

 In view of the fact that these types of fibers, so distinct peri- 



