104 J. B. JOHNSTON, 
is fusiform and has a central process reaching the cavity 
There is one thick dendrite arising from the peripheral end 
of the cell which very soon divides into several branches. These 
are much more slender than the dendrites of the cells of the type A, 
and are always smooth. The dendrites diverge widely and end in 
the middle and outer thirds of the tectum without any profuse 
branching. The neurite arises from the dendrite not far from the 
cell body, ascends to the middle third of the tectum, and turns 
laterally in the middle fibre zone. These cells have a peculiar de- 
licate appearance owing to their slender smooth dendrites. The one 
shown in Phot. 47 stands some distance from the middle line and 
has larger dendrites than those near the middle line. The cell in 
Phot. 48 is a little more typical. Its neurite makes a loop before 
turning laterally, which is very difficult to photograph. 
Type D: stellate cells in the molecular zone (Phots. 49, 52, 57). 
These cells present very wide differences in the size, form and 
position of the cell body, but agree in the character and disposition 
of their dendrites and in the course of their neurites. The bodies 
of these cells measure 12—20 by 16—32 u, and are found at all 
levels of the molecular layer. They are sometimes bipolar with two 
dendrites in a horizontal or oblique position (Phot. 52), sometimes 
stellate with three or more dendrites (Phot. 49) which may be short 
but very richly branched (Phot. 57). Near the surface of the tectum 
are many bipolar or stellate cells whose two or more dendrites 
spread parallel with the surface and send their branches deep into 
the substance of the tectum. Although these cells differ so widely 
in their form and position, they all have coarse and richly branched 
dendrites which break up at the same level in the tectum, viz., 
within the third and fourth fifths, measuring from within outward. 
A stronger reason for grouping these cells together is found in the 
course of their neurites. The great majority of the neurites of these 
cells enter the middle zone of fibres and the remainder join the 
superficial fibre zone. The fibres of both these zones enter in- 
discriminately into the formation of the tracts to the lobi inferiores, 
cerebellum, and the medulla. Afferent fibres to the tectum also run 
in these zones, but the efferent fibres arise mostly or wholly from 
the cells of the types C and D. Some of the neurites of the cells 
D go toward the dorsal decussation. These I regard as decussating 
fibres which run in the corresponding tracts on the opposite side. 
I conclude, therefore, that the neurites of these cells go to the lobi 
