Ranson, Fibers in Lesions of the Brain. 199 
It will be seen (Fig. 2) that the lines indicating the path of 
the knife above and below the white matter are not continuous, 
that below being more lateralward than that above, and running 
at a different angle. Since the injury was produced by a straight 
stab, this appearance can be explained only on the supposition 
that the areas of the cortex have shifted their relative positions 
during the process of growth. The shifting that takes place 
in the cortex over the corpus callosum is just the reverse, as 
seen in the sections near the anterior extremity of this same 
wound, where the part above the corpus callosum is more 
lateralward than the part below. 
Rat No. 3 was operated on when three days of age and 
killed forty-one days later. No sign of the injury could be 
found in the skull or the dura mater. On the brain a pale pink- 
ish groove, I.5 mm. in length, marked the line along which 
the knife had entered the cortex. 
When serial sections are examined, it is observed that the 
healing process is more complete than in the brains of the two 
older rats. The remains of unabsorbed blood are scarcely to 
be found; and at its anterior and posterior extremities the 
wound fades off so gradually into the normal brain substance 
that it is impossible by a study of serial sections to determine 
its exact limits. Its posterior extremity is slightly behind the 
end of the splenium, from which point it runs forward fora 
distance of a little more than 1.5 mm. _ By reference to Fig. 3 
the general appearance of the wound will be seen. _Lateral to 
the point of the lesion the corpus callosum has entirely disap- 
peared from the injured region. A small portion of its fibers 
remains intact near the middle line; but elsewhere the sub- 
stantia alba of the cortex rests immediately on the cornu 
Ammonis and the alveus. The alveus is absent for a short 
distance. The point near the middle line where the corpus 
callosum and alveus end represents the original position of the 
wound. By the large growth of fibers in the cortex medial to 
the lesion, the scar has been shifted lateralward until it has 
assumed the shape of a dilated V. 
The disappearance of the corpus callosum lateralward to 
