OLFACTORY CENTERS IN TELEOSTS PAT 
tundus. These fibers are both ascending and descending, although 
most of the ascending fibers apparently arise from the nucleus 
diffusus. It is difficult to make positive statements regard- 
ing the cells of origin of the dorsal ascending fibers of the basal 
forebrain bundle owing to rather poor Golgi impregnations of 
adult brains in this region (fig. 139); there is no question as to 
their presence, however, as many such fibers can be seen leaving 
these bundles rostrally. In Golgi preparations of the brains of 
young carp fibers may be traced, nevertheless, from a nucleus 
apparently corresponding to the nucleus cerebellaris hypothalami 
into the tractus strio-thalamicus. 
No strio-thalamicus fibers could be traced into the nucleus dor- 
salis, nucleus anterior thalami or nucleus lateralis tuberis, as Gold- 
stein found in the forms studied by him. It is probable that the 
fibers which Goldstein traces into the nucleus lateralis tuberis really 
arise from the nucleus magnocellularis, as will be shown later. It 
willthus be seen that the lateral forebrain bundle contains through- 
out, both ascending and descending fibers connecting all of the 
lateral and intermediate portions of the basal lobes with practi- 
cally all of the lateral and intermediate regions of the thalamus 
and hypothalamus, and also a part of the medial centers. It is 
not, therefore, the simple tract described by the earlier writers, 
but a complicated connection of paramount importance to the 
nervous mechanism. 
(S) The nucleus preopticus and its connections. The fiber 
connections of this nucleus have been little understood by the 
different writers on the brains of the lower vertebrates. John- 
ston (98), as noted earlier, traced fibers from it to the habenular 
ganglia; he also believed that secondary olfactory fibers termi- 
nate therein, although he could not demonstrate their presence. 
Johnston also observed fibers passing caudad, but could not 
trace them to their destination. In 1901 he observed fibers from 
it entering the tractus strio-thalamicus ventralis (tractus olfacto- 
thalamicus, probably pars intermedia). C. L. Herrick (’92) 
describes unmedullated fibers from the pars magnocellularis 
(nidulus praeopticus), which pass laterad into the optic tract 
region. Kappers notes similar fibers, which he traces ventro- 
