234 JB. JOHNSTON, 
and many stellate cells of the granular zone) which must be com- 
pared with the granules in Mammals. The latter cells should be 
reinvestigated with a view to discovering their neurites if they exist. 
2. The olfactory Tract. 
By all authors this tract has been represented as composed of 
the neurites of mitral cells and “Pinselzellen” alone, together with 
centrifugal fibres from the fore brain. I have shown that in the lower 
Vertebrates at least the tract contains neurites from a variety of 
other cells in the olfactory lobe. There is general agreement that 
the fibres of the tract end in the area olfactoria, nucleus taeniae, 
epistriatum (except EDINGER, discussed above). The crossed portion 
of the tract has been described by OSBORN (88), EDINGER, F. MAYER, | 
and others. 
3. Area olfactoria. 
EDINGER is the only author who had made a complete study 
of this region by modern methods previous to my preliminary com- 
munication (98a). According to EDINGER’s description of the 
Reptilian fore brain (96b), the area includes groups of cells in the 
base of the fore brain, at the anterior end, along the ventral sur- 
face, and at the posterior end. The posterior group, the nucleus 
taeniae, has been described by C. L. HERRICK (91) in Teleosts as 
the nucleus occipito-basalis, and is the same as KOLLIKER’s nucleus 
supraopticus in Mammals. I have discussed above the relations of 
this area and have shown that the fibres of the olfactory tract end 
here and in the epistriatum. From the area olfactoria, according 
to EDINGER, tracts run to three other centers: the epistriatum, the 
cortex, and the ganglion habenulae. The tract to the epistriatum, 
part of the tractus cortico-epistriaticus, is open to the same criticism 
which I have made upon the tract from the “Lobus cortex”. In my 
opinion, all connections between the olfactory lobe and the epistriatum 
are made directly by neurites of cells which are in immediate re- 
lation with the olfactory fibres in the glomeruli. The tract to the 
cortex, tractus olfactorius septi, comes from the front end of the 
area olfactoria and runs upward and backward in the septum to the 
Ammonshorn region of the cortex. This is the largest tract con- 
necting the cortex with other parts of the brain in Reptiles. It is 
scarcely to be expected that this tract will be represented in fishes, 
and yet the few fibres described above (page 144) which connect the 
