140 J. B. JOHNSTON, 
branches which extend widely through the epistriatum and striatum. 
The neurites grow more slender as they are traced farther from 
the cell and finally break up in end branches in the striatum. 
The level of the end branching varies greatly, sometimes being in 
the central part of the fore brain wall but frequently near the ex- 
ternal surface. Thus it happens that all parts of the striatum are 
reached by these short neurites. 
Fibres enter the epistriatum from three sources. Fibres from 
the olfactory lobe will be described below (page 152). Fine ascending 
fibres from the *tween brain (corpus mammillare, page 118) reach 
the epistriatum by way of the anterior commissure and end by fine 
ramifications in all parts of this nucleus. The neurites of the cells 
to be described below as cortical cells also end in the epistriatum. 
Striatum proper. — The cells of the striatum are slightly. 
smaller than those of the epistriatum, measuring 12—24 by 12—48 u. 
They are fusiform or stellate cells provided with two or more den- 
drites, which are usually devoid of fine spines, and spread ir- 
regularly through the striatum. These cells are occasionally pyra- 
midal in form and possess spiny dendrites, and are somewhat mingled 
with the cells of the epistriatum, so that the two kinds of cells can 
not be surely distinguished unless the neurites can'be studied. Further 
work since publishing my previous paper on this part of the brain 
(98a) has led me to conclude, however, that the two types of cells 
are more clearly distinct than I indicated in that paper. The neu- 
rites arise from the cell bodies or the basal part of the dendrites, 
are medium-sized fibres (coarser than those of the epistriatum cells), 
give off few and short or no collaterals, and enter some part of the 
tractus strio-thalamicus. The only fibres which I have found ending 
in the striatum are the short neurites of the epistriatum cells. 
2) Secondary olfactory Nuclei. 
There are three of these nuclei which occupy the ventral part 
of the fore brain. At the cephalic end of the fore brain are two 
groups of cells, one of which lies near the mid-ventral line opposite 
the Y-shaped division of the fore brain cavity into the two cavities 
of the olfactory lobes, while the second lies laterad from the first. 
In my previous paper (98a, p. 233) I have described these nuclei 
under the names of nucleus postolfactorius ventralis and lateralis, 
respectively. Both are ‘superficial in position. The cells of both 
nuclei are fusiform or stellate, with two or several dendrites which 
