92 
BULLETIN OB' THE LABORATORIES 
matter are large cells which change their direction to correspond with 
the direction of the tracts. This lateral area may have other functions 
than the dorsal or ventral area, but what the functions difference may 
be it is impossible to conjecture. 
The motor regions of the cortex are illustrated by Figs, i and 2, 
of Plate C. Fig. i is a drawing made to a scale illustrating a strip of 
cortex extending from beneath the giant cells nearly to the upper cell 
layer. The region is in the fronto-dorsal cortex near the median 
fissure. The two drawings are part of the same strip of cortex, the 
right end of No. i being near the dorsal surface. The forms vary 
considerably, some of the cells being simply fusiform, others inverted 
pyramids while there are a few aesthesodic cells among them. 
Fig. 2, is a camera drawing of the cortex from the deep pyramids 
to near the ectal layer. The apex processes extend beyond the cor- 
tex. The process of nutrition of the pyramids suggested elsewhere is 
well seen here. Several of the carrying corpuscles are often seen at 
the base of one pyramid. Fig. 4, Plate (’, is a camera drawing of a 
few of the deep pyramids or giant cells under the one-fifteenth 
objective. 4 
The general co?iclusions growing out of this investigation are 
briefly as follows : There is in the opossum a decided difference be- 
tween the aesthesodic and kinesodic cell types. Regions known to 
be sensory contain a large number of the type with clear round 
nuclei. The delimitation of the areas is, how^ever, very incomplete. 
This agrees well with the results of experiments. The two classes of 
cells are rarely unmixed in any area. In many cases at least the 
cortex cells give off processes which divide in the so-called neuroglia 
layer to form either a neuropilem or reticulum. It would seem that 
a more or less connected reticulum of fibres directly supplied by the 
cells is the simplest anatomical device which can in any way' be asso- 
ciated with unit states of consciousness. 
Idle probern of nutrition of the specific nerve cells is, we believe, 
somewhat simplified by the suggestion that there are special prolifer- 
ating centres in the brain base in which there are produced numerous 
corpuscles like Deiter’s cells which then migrate to the cortex and 
convey nutriment to the cells. The small and frequently shrunken 
bodies at the bases of pyramidal cells are interpreted as such nutrient 
bodies from the sources indicated, one of which is the post- rhinal lobe 
near the substantia perforata anterior. With reference to the fact that 
