274 ANATOMY OF THE CENTRAL XBHVOUS SYSTEM. 



fiber-masses, arranged in several bundles, converge toward this region. They 

 all originate from the corpus striatum, and terminate, so far as at present 

 known, in the nuclei of the stratum intermedium (ZwischenscMcht), espe- 

 cially in the substantia nigra and in the corpus subthalamicum, or at least in 

 its neighborhood, where there are found several other small ganglionic ac- 

 cumulations: the ganglia of the stratum intermedium. 



This radiation is no other than the posterior end of the tractus strio- 

 thalamici, which we have met with so frequently from the fishes on up to 

 man. It arises from the ansa leiitiformis, comes to view at the mesial bor- 

 der of the corpus striatum, crosses over the capsule, and, coming from the 

 side, streams thus into the separate ganglia of the stratum intermedium. 



That these fiber-bundles, designated as separate strata of the stratum inter- 

 medium, arise, at least in great part, from the corpus striatum, I conclude from the 

 preparations from the dog without forebrain, which have been repeatedly refen'ed 

 to here. 



The region ventral to the thalamic ganglia and to the ansa peduncularis 

 (Fig. 169) is traversed by fine longitudinal fibers, which, arising from the 

 olfactory lobe, pass to this region in a straight line. We will designate them 

 as the olfactory hundles of the interbraiii. They may be traced as far as into 

 the region of a ganglion-complex which, situated at the base of the inter- 

 brain, there projects as a small hemisphere on the base of the skull. 



It is called the corpus mamillare, and is very much larger in the osmatic 

 vertebrates than in the Primates (compare Fig. 141). In Figs. 176 and 178 

 it falls exactly in the plane of section. 



Down toward the corpus mamillare there passes through the central 

 ventricular gray matter the bundle of the pillar of the fornix from the cornu 

 Ammonis and the marginal convolution. The bundle appears to end in it 

 partly on the same side, partly on the opposite. The small decussation 

 dorsal to the corpus mamillare, which contains, in part at least, fornix 

 fibers, is called the anterior decussation of the regio subthalamica. In Figs. 

 133 and 134 trace the course of the fornix from the cornu Ammonis on 

 down as far as the region just described. Frequently consult these figures, 

 also, for the following description : — 



The corpus candicans consists, as Gudden's experiments showed, of 

 three nticlei. The most lateral nucleus sends its pedicle (pedunculus corporis 

 mamillaris) far down into the oblongata; from the posterior of the two 

 mesial nuclei arises a thick bundle which ascends into the thalamus and 

 is lost in its tuberculum anterius. This tractus thalamo-mamillaris 

 (bundle of Vicq d'Azyr) is entirely visible in Fig. 144, and, for a part of 

 its course, in Fig. 174. Close beside this, coming from the more anterior 

 nucleus, or ganglion, there ascends a small fiber-strand toward the thalamus. 



