OLFACTORY CENTERS IN TELEOSTS , 219 
habenular ganglia as it passes them, but such could not be dem- 
onstrated with certainty. 
(6) Fasciculus medialis hemisphaerii. This was observed first 
by Bellonci in Anguilla, and by him considered to be an olfactory 
tract of the second order from the olfactory bulbs to the nuclei 
rotundi. The question of the presence of such fibers in the carp 
has already been discussed. Edinger similarly traced a part 
of the fibers of the medial olfactory tract to the diencephalon, 
the tractus ad lobum inferiorem. C. L. Herrick identified the 
tract, but states that it originates in the mesaxial lobe (nucleus 
medianus and nucleus supracommissuralis of the corpus pre- 
commissurale), decussates as the axial commissure (anteriorcom- . 
missure), and then extends to the infundibulum. Herrick calls 
the rostral end the ‘basal cerebral fasciculus,’ while the dien- 
cephalic part he terms the fornix tract. Johnston (’98) describes 
the bundle as the tractus strio-thalamicus ventralis, passing cau- 
dad, without decussation, to end in the inferior lobes. In 1901 
he points out that these fibers are largely descending, originating 
chiefly from the nucleus postolfactorius ventralis and to a less 
extent from the nucleus preopticus. It also contains ascending 
fibers from the corpus mammillare, most of which decussate in 
the anterior commissure to end in the epistriatum of the opposite 
side. Kappers describes the bundle in the teleosts as originating 
in his epistriatum (corpus precommissurale) and ending uncrossed 
immediately lateral to the nucleus rotundus. Goldstein gives 
the same origin for the fibers, but states that they decussate in the 
nucleus posterior tuberis. He notes also that the tract consists 
of more than one bundle, but fails to observe any difference in 
the connections of the different components. 
A careful study of this tract in the carp shows that, instead of 
being a simple, single tract, it is really a complex of six fiber bun- 
dles each with a distinct course and connections. It likewise 
becomes apparent that Kappers, Goldstein, Johnston, ete., 
observed only a part of these components, which accounts for 
the differences in the course and connections of the tract as 
described by them. 
