OLFACTORY CENTERS IN TELEOSTS nA | 
There are also ascending and descending unmedullated fibers 
running between the nucleus posthabenularis and the nucleus 
intermedius (tr. intermed. posthab. and tr. posthab. intermed.). 
Connections between the nucleus entopeduncularis and the 
nucleus intermedius may likewise be found (tr. intermed. entoped. 
and entoped. intermed.). 
All of these latter short connections contain few fibers and in 
many cases form little more than a reticular network between 
different parts of closely related regions; they can not be demon- 
strated by means of Weigert preparations, but come out only 
in the silver methods, particularly the Ram6én y Cajal. They are 
chiefly important in emphasizing the intimate relation between 
all parts of the brain, and particularly, closely related morpholog- 
ical areas, through the formatio reticularis. 
This covers all of the direct olfactory connections which could 
_ be identified, but does not include the further connections of the 
different tertiary thalamic centers with other points in the dien- 
cephalon, mesencephalon, cerebellum, medulla and spinal cord. © 
Some of these are shown, however, in the Weigert transections. 
It is expected that an article will appear later in which the mor- 
phological relations and functions of the different diencephalic 
centers will be taken up in detail, in which these further connec- 
tions will be brought out. Until that time, it is not deemed wise 
to discuss in detail the morphological bearing of the thalamic 
olfactory connections, although some points will be taken up 
later in the interpretation of results. 
5= THE CONDUCTION PATHWAYS 
At this point it may be well to point out the different pathways 
which an impulse of a given character may follow. Of the vari- 
ous possible, anatomically demonstrated paths open to a given 
impulse, the one chosen under given conditions can be unques- 
tionably accepted only when physiological evidence can be offered 
in support. Nevertheless, impulses must follow conduction paths, 
and we may, therefore, plot out anatomically extensive impulse 
pathways with an exceptional degree of accuracy, as is shown in 
the cases where a physiological check has been used. 
