Cytological Structure, Hypothalamic Nuclei, Functional Connections 79 
HYPOTHALAMIC NUCLEI MADE UP CHIEFLY OF 
CENTRAL SOMATIC EFFERENT NEURONS 
Nucleus Hypothalamicus Dorsomedialis: This nucleus lies 
lateral to the third ventricle (Fig. 3) and is most apparent just 
anterior to the middle of the tuber cinereum. Its boundaries are 
not clearly defined, particularly with reference to the nuclei in 
the anterior hypothalamic area and the nucleus filiformis prin- 
Cipalis, Its constituent neurons are central somatic efferent and 
associational ; the former being much the more abundant. Many 
of the central somatic efferent neurons are slightly fusiform and 
are oriented so that the long axis lies parallel to the wall of the 
third ventricle. The nuclei of ail the neurons of this group are 
characterized by very little chromatin except that of the nucle- 
olus. This gives the group as a whole a relatively clear ae 
ance. Efferent fibers arising in this nucleus enter the periven- 
tricular system (Gurdjian, 1927; Krieg, 1932). 
Nucleus Hy pothalamicus Ventromedialis: |The dorsal por- 
tion of this nucleus fuses with the nucleus hypothalamicus dor- 
somedialis (Fig. 3 A). The nucleus hypothalamicus periven- 
tricularis ventralis and the nucleus hypothalamicus periventri- 
cularis dorsalis form its medial boundary throughout part of its 
“xtent. The component neurons are central somatic efferent and 
associational. The former form the greater part of the nucleus. 
“ey are peculiar for neurons of this type in that the processes 
are relatively very coarse, and considerable chromidial substance 
“xtends into the proximal portion of these large processes. The 
cell body also contains a slightly larger amount of chromidial 
Substance than is seen in typical central somatic efferent neurons. 
These structural peculiarities suggest that the functional con- 
ections of these neurons may be effected at a greater distance 
from the hypothalamus. The distribution of their axons has not 
been determined. 
Anterior Hypothalamic Area: ‘This group is located in the 
dorsal part of the anterior portion of the hypothalamus (Fig. 3 
