OF DENISON UNIVERSITY. 
93 
the cells regarded as kinesodic generally have their apical processes 
directed peripherad (the converse being the case with the aesthesodic,) 
it must be said that too much confidence should not be placed in this 
distinction. We now believe that the direction of the apical process 
is to be interpreted as a function of the direction from which the cell 
has migrated. We have shown in a series of papers that there is 
morphological and embryological evidence that the cortical cells are 
not formed in situ but have migrated from proliferating areas primarily 
found in the axial lobe. This suggestion has recently been greatly 
emphasized by the discovery that the axial lobe of fishes contains 
well marked areas of the two kinds of cells sustaining the proper re- 
lations to the tracts to enable us to identify them as motor and sensory 
respectively. It is believed that the motor areas of the cortex are 
supplied by cells which migrate from before backward and first lodge 
in the cortex, whence many subsequently migrate to deeper zones. 
Such migrating cells retain their connection with the peripheral source 
by means of the long apical processes. Sensory cells, having in many 
cases a different path of migration, naturally occupy dilferent positions. 
In view of the recent results of Golge’s method of staining, it would 
be premature to decide how far these processes are simply nutritive 
and how far actually nervous. It is significant, however, that the 
processes of nutrition apparently go on at the base of the cell as indi- 
cated by the nutritive nuclei there collected. 
PLATE A. 
A series of transverse sections through the cerebrum of the opossum. 
Fig. I. Section through the olfactory lobes. 
Fig, 2. Section at the junction of the crus and post-rhinal lobe near the 
union of the rhinalic and splenial fissures. 
Fig. 3. Section through the fore part of the cerebrum. 
Fig. 4, vSection through the anterior commissure and fornix body. 
Fig. 3. Section at the caudal part of the anterior commissure, showing 
the encroachment of the radix lateralis mesad and the dorsal sac 
Fig. 6. Section through the praethalamus and chiasm 
Fig. 7. Section through the mesencephalon at the posterior commissure 
and hippocampus. 
Fig. 8. Section through the occipital portion of the cortex and nates. 
Fig, 9. Section through the cerebellum and pons. 
