96 Anatomy of the Nervous System 



(4) The supracommissural bundle also connects with the basal 

 nucleus, while anteriorly it partly runs into the paraterminal body of the 

 septum and partly turns back under the anterior commissure to join the 

 medial forebrain bundle. The latter portion can be followed into the 

 praeoptic and hypothalamic regions in the rat. 



(5) The stria medullaris bundle has already been described (p. 74). 

 The stria terminalis is accompanied in the reptiles and in mammalian 



embryos by a ridge of gray matter, the hed of the stria termiyialis. In 

 adult mammals, this is reduced along the main part of the course of the 

 stria to the condition of a few scattered cells among the fibres of this tract. 

 At the anterior end of the stria, however, there remains a considerable 

 mass of gray matter near the anterior commissure, which is particularly 

 largely developed in the rat (PI. XXL). This is continuous with the gray 

 matter surrounding the commissure (the bed of the anterior commissure) 

 and extends forward and downward over the medial surface of the anterior 

 limb of the commissure (p. 97) to merge with the medial part of the head 

 of the caudate nucleus and with the nucleus accumbens (p. 106). Thus 

 these latter structures are seen to belong to the olfactory system, of which 

 the bed of the stria terminalis is a part. They are, moreover, both con- 

 tinuous anteriorly with a mass of secondary olfactory cells in the basal 

 wall near the olfactory bulb, which mass has received the name of anterior 

 olfactory nucleus (Fig. 4).^ 



Other fibres connecting the amygdala with several different regions 

 are contained in the rather diffuse longitudinal amygdalo-pyriform associa- 

 tion bundle (sagittales Ldngsbiindel , tractus cortico-amygdaloideus) shown in 

 Pis. XIX. and XX. 



A crowded group of large cells situated at the ventral 

 surface immediately in front of the optic chiasma on each 

 side, and exitending posteriorly dorsal to the latter, is the 

 praeoptic nucleus {nucleus praeopticus, nucleus magnocellularis 

 praeopticus, ganglion basale opticum), which is related to the 

 paraterminal body both in its origin and in its connections, 



^Authorities differ as to the definition of this nucleus. According 

 to Herrick (Jour. Comp. Neur., vol. 37, pp. 317-359) it includes the part 

 mentioned on p. 90 as anterior end of the lateral olfactory gyrus and 

 extends back from the olfactory bulb above the anterior end of the 

 tuberculum olfactorium. A distinct lamina superficial to the anterior end 

 of the lateral olfactory gyrus is the pars externa of the anterior olfactory 

 nucleus of Herrick. See particularly Gurdjian '25 and Obenchain '25. 

 The part marked noa in PI. XXIII belongs to the caudate nucleus. 



