OF DENISON UNIVERSITY. 
39 
Nearly the whole upper surface of the cerebral hemisphere of the 
left side was exposed. The loss of blood was very moderate. 
The electrodes were introduced at point i, Fig. 2, Plate XI, about 
9 mm. from the median fissure and a little in advance of the line pass- 
ing through the anterior angle of the eye. The result was a forward 
and inward motion of the right fore leg. 
At point 2, the introduction of the electrode gave an undefined 
movement of right fore leg. 
At point 3, about 7 mm. from the median line and separated from 
I by a faint sulcus, the stimulation produced a flexion of the pes on 
the crus and elevation of right hind leg. 
At 4, a movement of the right hind leg, as at 3, and a slight ro- 
tation of the fore leg inwards. 
At 5, about 3 mm. from the median line, the stimulation pro- 
duced an extension and divarication of the digits of the right foot. 
At 6, the fore leg was elevated and flexed, and with a little stronger 
current the hind leg was also elevated and flexed. 
At 7, there was an extension of the toes corresponding to the 
movements produced at 5, of the opposite side. 
Perhaps more important in its bearing on the present subject is a 
set of experiments upon the opossum, of which, unfortunately, no very 
exact data have been preserved. The configuration of the hemispheres 
as well as the details of structure resemble very closely those of rodents. 
Moreover, such hints as we have of the development of the Rodentia 
indicate a common origin for the two groups and comparatively slight 
subsequent differentiation. It, then, would not be surprising if a con- 
siderable similarity of distribution in the cortical elements should be 
proven to exist. On the other hand, the existence of an apparent 
homologue of the crucial sulcus near the front of the cerebrum would 
lead one to expect the aggregation of the motor elements near this 
sulcus. The experiments in this case were made with a Grenet cell 
and DuBois-Raymond coil, with the secondary coil at about 8 cm., the 
current being applied by a pair of platinum electrodes separated by 
about 3 mm. Stimulation of the region about the crucial sulcus (so 
called) resulted in movements ot the anterior extremity, but the diffi- 
culty in controlling the flow of blood interferred with close analysis. 
The area on either side of the median fissure responded with various 
poorly localized contractions of the trunk. About 6-8 mm. posterior to 
the crucial sulcus and 4-5 mm. from the medial line is an ill-defined 
