188 RALPH EDWARD SHELDON 
of the nucleus olfactorius anterior. It is certain that a few of the 
stellate cells send their neurites into the hemispheres, but such 
could not be demonstrated with certainty for all. Many fusi- 
form cells of the type shown in fig. 13 lie near the center of the 
bulb with two processes extending to either margin. These cells 
likewise send their neurites to the hemispheres (fig. 21). Cells 
of the types shown in figs. 15, 16, 18, 20 may be found in any part 
of the nucleus olfactorius anterior, with their processes extending 
nearly equally in all directions. Small granule cells, of the type 
shown in fig. 19, are common in the center of the bulb, where they 
apparently function as association cells, as no neurites entering 
the crura could be demonstrated. The mitral cells undoubtedly 
correspond with the mitral cells of all other vetebrates, so far 
as studied; there is some question, however, regarding the com- 
parative morphology of the smaller cells throughout the verte- 
brate series. Apparently, as is shown also by Johnston, the stel- 
late cells in lower vertebrates are connected with the glomeruli 
and hemispheres, much as are the mitral cells; as an ascent is made 
in phylogeny, however, these cells may either disappear or may 
metamorphose into mitral cells. The typical stellate cells of the 
carp as shown in figs. 14, 17, are undoubtedly similar to the stel- 
late cells of the granular zone of Acipenser, as described by John- 
ston; there is the same relation to the glomeruli, the position in 
the bulb is the same, and the central processes take the same 
course. Fusiform cells of the type shown in fig. 13 are probably 
the homologues of Johnston’s spindle cells of the granular zone, 
although no neurites were traced from these cells into the crura. 
The type found in figs. 15 and 20 probably corresponds to John- 
ston’s cells with short neurites, Golgi type II cells. Cells of Cajal 
were not identified with certainty. The granule cells of the carp 
are apparently simply intrinsic association nerve cells, differing, 
therefore, from the granule cells of Acipenser. 
The fiber tracts of the olfactory bulb will be taken up later, in 
connection with the fiber systems of the cerebral hemispheres. 
