150 J. B. JOHNSTON, 
shaped and stand in a radial position with ‘their dendrites directed 
radially outward and not diverging greatly. The cell bodies measure 
8—16 by 24—40 u. There is typically a central process which 
reaches the cavity, but the cells are sometimes situated far from 
the cavity and this process is absent. When present, the central 
process gives rise to the neurite which runs close to the cavity 
toward the fore brain, giving off one or more long slender collaterals 
which rise toward the glomerular zone. From the distal end of the 
cell arises a single dendrite which divides into several branches, 
some or all of which enter into, or themselves form, glomeruli. 
6) Granule cells (Fig. Q). — These are rounded or pyramidal cells 
measuring 8—32 u in their greatest diameter, which occur at all 
levels of the granular zone. I quote here the description previously 
given of them (98a, p. 225): “Their peripheral processes rise to the 
glomerular zone and end in olfactory glomeruli; either forming, 
with olfactory fibres, glomeruli into which no other central elements 
enter, or entering glomeruli formed chiefly by other cells described 
above. From the central end of the cell arises a slender, uniform, 
slightly varicose neurite which runs either centrally or backward — 
that is, in the direction of all other neurites. I have also found 
in some cases several short slender dendrites arising from the 
central end of the cell about the base of the neurite.” 
7) Cells of Casa. — The cells to which I have given this name 
in my preliminary paper (98a, p. 226) are very striking elements 
which are present in small number in most of my preparations. 
The cell body is stellate or elongated and measures 8—2U by 24—40 u. 
The dendrites are large and many branched. All the branches are long, 
comparatively straight and uniform in diameter. Some of the branches 
are very slender and have the appearance of neurites. The greatest 
expansion of the dendrites exceeds one millimeter and is sometimes 
equal to half the diameter of the olfactory lobe. A good idea of the 
general appearance of these cells is given by Phots. 72 and 84, 
although many of the slender dendrites can not be brought into the 
plane of focus so as to show in a photograph. Some of the den- 
drites enter into the formation of glomeruli, but most of them end 
in the glomerular zone without rich branching. They may receive 
stimuli from the collaterals of the centrally directed neurites of other 
cells, or from the centrifugal fibres, if such exist. The neurite, which 
is a very slender, varicose fibre, arises from the cell body or from 
the basal part of one of the large dendrites and runs centrally. 
