412 Journal of Comparative Neurology and Psychology. 



of KoLLiKER that the substantia reticularis alba is composed of 

 sensory bundles of the second order and that the substantia 

 reticularis grisea is a sensory field of the third order, designed 

 to distribute sensory excitations from the V, IX and X nerves 

 (and also, it should be added, from the VII nerve) over a large 



cerebellar 

 tracts 



Fig. 21. Portion of a sagittal section of the brain of Minytrema melanops 

 (Raf.). GOLGI method. X 4°- 



The section is quite oblique, the cephalic end and the dorsal side being inclin- 

 ed toward the median line. It passes through the ascending secondary gustatory 

 tract at the point where it enters its terminal nucleus under the cerebellum (the 

 cephalic end of the figure being at the left). The spinal V tract [sp.V.tr.) is 

 cut close to its superficial origin from the periphery. A single neurone of the 

 most dorsal part of the motor V nucleus is impregnated, one of its dendrites 

 crossing the mesial side of the gustatory tract to ramify in the most ventral and 

 caudal part of the layer of chief tertiary gustatory neurones, a single one of 

 which is impregnated. The tertiary gustatory path does not lie in the plane of 

 this section (cf. Fig. 23). 



field of motor nuclei of the oblongata. This definition, it will 

 be observed, carries also the secondary gustatory nucleus, save 

 that in addition to direct relations of the secondary termini with 

 the motor nuclei, like the trigeminal connection just described, 

 there is here, as we shall see, a much more extensive develop- 

 ment of tertiary neurones for connections of a higher order in 



