THE FOREBRAIN OF THE ALLIGATOR a1 
pass in both directions. It serves, then, partly as a discharge 
path from the parolfactory areas (tractus parolfacto-hypotha- 
lamicus and tr. olfacto-peduncularis) and perhaps also from the 
tuberculum olfactorium, and partly as a pathway by which vis- 
ceral impulses from the hypothalamic region may reach the 
medial parolfactory area (tractus hypothalamo-parolfactorius) 
and, either with or without a synapse there, the hippocampus. 
Fibers connecting the parolfactory areas and the hippocampus 
run on the medial and lateral borders of the medial forebrain 
bundle. 
Lateral forebrain bundle (figs. 9, 16, to 21, 37, 45, 46, L. F. B.). 
This bundle is made up in part of axones arising from the pro- 
jection cells of the striatum. It runs ventro-medialward, joins 
the medial forebrain bundle on its lateral side, and then passes 
caudad into the diencephalon. ‘This is the tractus strio-thalam- 
icus of DeLange and Unger. 
Besides these components of the lateral forebrain bundle which 
carry impulses from the striatal region, there are fibers from the 
lateral and medial nuclei of the thalamus which run ventral- | 
ward and join the other fibers of this bundle and then go for- 
ward to the striatum. These facts are known because axones 
er the cell bodies of the lateral nucleus and nucleus rotundus 
have been seen to join this bundle (tractus thalamo-striaticus, 
or thalamic projection tracts). 
There is a second thalamo-striatal path which runs from the 
anterior nucleus of the thalamus to the ventro-lateral small 
celled part of the hemisphere (that part which is Johnston’s 
nucleus caudatus). This has been described by Johnston, 
DeLange, and others. 
GENERAL DISCUSSION 
The problems of forebrain morphology and especially those 
dealing with the evolution of the cortical areas have always had 
a peculiar fascination for the comparative neurologist. The 
broad lines and many of the details of forebrain development 
throughout the vertebrate series have been brought out by such 
observers as Edinger, Elliot Smith, Johnston, Herrick, and 
Kappers. 
