THE FOREBRAIN OF THE ALLIGATOR 367 
medial nucleus and a few of them enter the anterior end of the 
nucleus preopticus. This fiber tract has been seen and more 
fully described by Johnston (715, p. 407) in the brain of the 
turtle. Because of the deposit of silver on the outer surface of 
the Cajal material in this region, it has been impossible to study 
this fiber tract in the alligator as carefully as would be desirable. 
Apparently, however, it is made up, in part, of short fibers which 
form synapses among the cells of the diagonal band (see the de- 
scription of this nucleus). The significance of this tract les in 
the opportunity it gives for a close connection between the lat- 
eral and medial olfactory areas of the hemisphere (figs. 16 to 19). 
Stria terminalis 
This stria consists of two divisions. 
The commissural portion (St. term. p. com., fig. 18). Slight- 
ly anterior to the level of the anterior commissure fibers may be 
seen passing from the region of the pyriform lobe, the nucleus 
of the lateral olfactory tract (particularly its dorsal portion), 
and the extreme ventro-lateral portion of the dorso-lateral area, 
directly medialward over the dorsal surface of the medial fore- 
brain bundle (VM. F. B.). Most of these fibers cross to the oppo- 
site side through the anterior commissure and distribute to the 
corresponding regions of the other half of the brain. Some of 
the fibers end in the bed nucleus of the anterior commissure of 
the same and the opposite side. 
The preoptic portion (St. term. p. preop., figs. 19 to 21). This 
part is formed by fibers which distribute to the region of the 
pyriform lobe, the ventro-lateral part of the dorso-lateral area 
and the nucleus of the lateral olfactory tract from the posterior 
end of the region reached by the commissural portion of the 
stria terminalis to the caudal end of the basal portion of the 
hemisphere. This preoptic division turns medialward and cau- 
dalward, lying ventral to the posterior division of the lateral 
cortico-habenular tract and dorso-lateral and dorsal and in close 
relation with the olfactory projection tract of Cajal and its 
accompanying cell band—the interstitial nucleus. This preop- 
