The ornamental design for an apparatus for stimulation of the nervous system, as shown and described.
FIG. 1 is a perspective view of an apparatus for stimulation of the nervous system according to the present invention;
FIG. 2 is an enlarged perspective view;
FIG. 3 is a rear perspective view thereof;
FIG. 4 is a left side elevation view thereof;
FIG. 5 is a top view thereof (which is identical to the front and rear views); and,
FIG. 6 is a right side elevation view thereof.
The broken line showing in the drawings is included for the purpose of illustrating environmental subject matter of the apparatus for stimulation of the nervous system and forms no part of the claimed design.