And in the very highest animals, probably only monkeys and man, we find that the hemispheres have gone so far with their jealousy as to usurp the function of sensation.

This is seen in the singular fact that with a monkey or man the removal of the cortical centres makes the animal permanently blind or deaf, as the case may be, while in the lower animals such removal does not have this result, so long as the "second-level" organs are unimpaired.

The brain paths of the functions of the second and first levels taken together constitute the so-called "voluntary circuit" (see Fig.

2).
In addition to this general demarcation of functions as higher and lower--first, second, and third level--in their anatomical seat, many interesting discoveries have been made in the localization of the simpler functions in the cortex itself.

The accompanying figures (Figs.