E. Lindon Mellus 229 
7 mm. in length and its lower extremity reached and barely crossed the 
pre-central sulcus in the upper portion of the middle third of its ascend- 
ing ramus. The hemorrhage at the surface of the wound was very slight 
and was quickly and easily checked. The animal quickly recovered from 
the anesthetic and though carefully watched there was no evidence of 
disturbed function. At the end of ten days it was killed with chloroform, 
the brain removed, hardened, and stained by the Marchi method and cut 
into horizontal sections. 
Examination of the hardened brain showed that the operation had 
been followed by considerable hemorrhage and consequent areas of soften- 
ing. In the highest level the knife had passed quite through the corona 
radiata and reached the base of the cortex covering the mesial surface 
of the brain. 1mm. below this level the knife reached the longitudinal 
fissure and, passing downward through the genu of the corpus callosum, 
amputated about 2 mm. of the left half from the anterior extremity of 
that structure (Fig. 3). Considerable hemorrhage had taken place at 
this point, the blood working forward between the membranes and the 
cortex of the mesial surface of the left hemisphere almost to the frontal 
pole, and backward upon the upper surface of the corpus callosum within 
the longitudinal fissure. There were spots of softening in the cortex of 
the mesial surface of the left hemishphere just anterior to the lesion, 
not extending so far forward as the clot. There were spots of softening 
in the anterior and posterior extremities of the superior surface of the 
corpus callosum, but not extensive. The central portion of the corpus 
callosum was uninjured. There was slight infiltration and softening of 
the septum lucidum just anterior to the foramen of Monro. At one point 
in the level of the base of the external wound the blood had forced its way 
around the frontal pole and there were two small spots of softening in the 
cortex beneath the clot near the frontal pole. In the level of the foramen 
of Monro the point of the knife fell just short of the middle line, but 
entered the ventricle, into which there had been slight hemorrhage, which 
was probably the cause of the softening in the septum lucidum mentioned 
above. In this level the wound passed through the caudate nucleus, sever- 
ing the anterior fourth from the body of the nucleus (Fig. 4). Below 
the level of the foramen of Monro the line of incision drew nearer and 
nearer to the lenticular nucleus, and in the level of the posterior commis- 
sure just touched its anterior extremity, extending from the base of the 
cortex of the laryngeal area, just anterior to the process of corona radiata 
belonging to the Rolandic operculum, to the ventricle (Fig. 6). Just 
below these levels the incision fell short of the ventricle, and the hxemor- 
