462 C. JUDSON HERRICK 



toward the stria medullaris. I shall term the latter the nucleus 

 of the tractus cortico-habenularis. These two nuclei have been 

 differentiated from the single commissural nucleus of Amphibia, 

 and they represent here also the rostral end of the pars ventralis 

 thalami (cf . fig. 69) . Fibers (probably collaterals) from the com- 

 missure hippocampi and tractus cortico-habenularis end freely 

 among their cells. Other fibers from the same sources pass 

 through the nuclei to enter the stria medullaris and still others 

 pass between the nucleus of the tractus cortico-habenularis and 

 the corpus striatum complex. The significance of the latter fibers 

 is uncertain. Both nuclei, like their precursor in the Amphibia, 

 clearly represent a correlation center of some sort interpolated 

 in the cortico-habenular path, probably for efferent discharge 

 into the somatic motor centers. 



The nuclei of the septum, including the bed nuclei of the anterior 

 commissure and commissura pallii anterior and posterior, belong 

 morphologically in the pars ventro-medialis of the hemisphere 

 and constitute a correlation center interpolated between the olfac- 

 tory bulb and the cortex hippocampi on the one hand and the 

 hypothalamus on the other hand. In amphibians, reptiles and 

 mammals columna fornicis fibers (or collaterals) end in this nu- 

 cleus, which is also related by association tracts with the corpus 

 striatum complex in the ventro-lateral part of the hemisphere. 

 Its chief path of efferent discharge is into the hypothalamus. 

 (For the mammalian relations see Ramon y Cajal, '04, p. 1054). 



In reptiles the tractus cortico-habenularis arises from the col- 

 umna fornicis and commissura pallii anterior within the precom- 

 missural body, with whose cells it has a collateral connection, 

 then passes by way of the stria medullaris to the habenula where 

 correlation is effected with the somatic sensory centers of the pars 

 dorsalis thalami before the discharge into the ventral tracts of the 

 interpeduncular region. 



The nuclei of the hippocampal commissure and tractus cortico- 

 habenularis have still a different significance, having been differ- 

 entiated from the rostral end of the pars ventralis thalami. They 

 receive collaterals from the tracts to which they are related and 

 are connected laterally with the striatum complex. In brief, 



