236 C. JUDSON HERRICK 
tromedial areas of the septum, preoptic nucleus, and hypothala- 
mus. In the frog the lateral connections of this system center 
in the amygdala, with more or less extensive connectio~s with the 
overlying pyriform lobe. Its fibers pass partly ventrai'v of the 
lateral forebrain bundle and partly dorsally of it. 
The fibers of the ventral component which can be followed 
forward from the amygdala to connect with the nuclei of the 
septum and rostral end of the preoptic nucleus form the diagonal 
band. The ventral fibers which are followed spimalward form 
the ventral projection tract, whose medial connections are 
-unknown, probably chiefly with the caudal end of the preoptic 
nucleus. 
In a similar way the fibers of the dorsal component of this 
system form a continuous sheet. Those which are followed for- 
ward from the region of the amygdala passing above the lateral 
forebrain bundle to connect with septal areas form the stria ter- 
minalis; those which are followed spinalward to connect with the 
hypothalamus form the dorsal olfactory projection tract. It is 
probable that both dorsal and ventral components contain corre- 
lation fibers passing in both directions between the lateral and 
medial terminal nuclei throughout their entire extent. 
The term olfactory projection tract was first used by Cajal as 
a synonym for the stria terminalis of lower mammals. The inti- 
mate relation of the diagonal band of Broca with this system was 
recognized by Johnston in the turtle brain (15, p. 407), and 
Crosby (’17) described relations of these tracts to the amygdaloid 
complex in the alligator which are very closely similar to those 
of the frog. Both of these authors describe in reptiles a com- 
ponent of the amygdaloid complex (medial large-celled nucleus 
of Johnston, ventromedial nucleus of Crosby) whose topographic 
relations and fiber connections resemble those of the amygdala 
of the frog as described above (see beyond, p. 269). 
Crosby separated the olfactory projection tract of Cajal into 
two systems: (1) a system related on the medial side with the pre- 
optic nucleus (and septum?), and (2) a system directed farther 
caudad to connect with the hypothalamus. To the first she ap- 
plied the old term stria terminalis; for the second she adopted 
