Cytological Structure, Hypothalamic Nuclet, Functional Connections 71 
is the large anterior nucleus which occupies the greater portion 
of the tuber cinereum; the other the relatively minute postero- 
lateral nucleus. In a fundamental study of the hypothalamus in 
man, Malone (1910) recognized seven nuclei on the basis of the 
cytological structure of their constituent neurons. 
Greving (1923) discussed the fiber tracts related to the hy- 
pothalamic nuclei, as observed in Bielschowsky preparations. 
Later (1928), he described seven nuclei in the tuber cinereum 
in the human hypothalamus and seven more in the mammillary 
body and neighboring regions. In an extensive study of the 
hypothalamus in the albino rat, reported in a series of papers, 
Gurdjian (1925, 1926, 1927) described various fiber connections 
of the hypothalamic nuclei and classified these nuclei mainly on 
the basis of their relative isolation by fiber tracts or undifferen- 
tiated gray matter. By using the delimitation of neuron groups 
as a criterion, in contrast to the criterion of cell types used by 
Malone, Rioch (1929) was able to identify twenty nuclei in the 
hypothalamus in the dog and the cat. 
Griinthal (1929) found the nuclear pattern in the hypothal- 
amus in the dog similar to that in the rat, but somewhat simpler. 
He (1930) also reported that the lower mammals present a more 
othalamus than the more 
highly specialized ones. This, according to his observations, is 
true also in human ontogeny, that is, there i i 
plification of the nuclear pattern as the huma 
He observed more nuclear divisions in the € 
newborn. 
n embryo develops. 
mbryo than in the 
ons of the substantia 
According to Morgan (1930) the neur 
e cells in the central 
srisea centralis are among the smallest netv 
Particularly in those areas in which the neurons a A 
aggregated. Morgan agreed with Malone that, although the 
