234 JOHNSTON. [VOL. I. 



ders of the stellate and spindle cells of the granular zone. The 

 terminal branches are thickened and varicose. 

 . The nucleus postolfactorius lateralis is much larger than the 

 ventralis. It is made up of multipolar cells similar to those 

 of the ventralis, measuring 16 to 20 by 20 to 24 p. Their 

 axis cylinders, together with fibers from the anterior end of 

 the striatum, form a bundle of fibers which runs ventro-poste- 

 riorly over the lateral surface of the fore-brain (Fig. 4, C). At 

 the optic thalamus the bundle turns mesad, plunges through 

 some of the more mesial optic bundles, and continues into the 

 'tween-brain with the tractus strio-thalamicus medius, on the 

 lateral surface of which it forms a distinct bundle. Its desti- 

 nation I have not yet worked out. The fibers which end in the 

 lateral nucleus postolfactorius come from the olfactory lobe, 

 but from what cells of the lobe I cannot at present say. They 

 seem to be those axis cylinders which take the most direct 

 course to the fore-brain and do not run close over the central 

 cavity; hence, some of the axis cylinders of the granules, the 

 cells of Cajal, the mitral cells, and the stellate cells of the 

 glomerular zone. 



There seems to be a third nucleus occupying the antero- 

 dorsal angle of the fore-brain having relations similar to those 

 of the lateral nucleus. Since its cells have been impregnated 

 in only a single series, I cannot describe it further. It may be 

 a nucleus postolfactorius dorsalis, or it may belong to the 

 epistriatum. 



In addition to the fibers which run from the nuclei post- 

 olfactorii to the ventral portion of the 'tween-brain, there are 

 several small bundles of fibers which connect these nuclei with 

 the ganglia habenulae. Tracing the fibers forward from the 

 ganglion of habenula, the bundle breaks up in the posterior 

 dorsal portion of the fore-brain into several small bundles, 

 which diverge like the ribs of a fan and . penetrate to the ven- 

 tral part of the fore-brain throughout its entire length. Here I 

 have been unable to find either terminal arborizations or cells 

 of origin, owing in some cases to imperfect impregnation and 

 in others to the great number of fibers of other tracts, making 

 it impossible to trace these through successive sections. How- 



