With these two precautions taken, the image on the final fixation-point is like either 3, 4, or 5.  Shape 5 very rarely appears, while the trained subject sees 4 and 3 each about one half the times; and either may be seen for as many as fifteen times in succession.

Shape 4 is of course exactly the appearance which this experiment takes to be crucial evidence of a moment of central anaesthesia, before the image is perceived and during which the stimulation of the handle h completely elapses.  Eight subjects saw this phenomenon distinctly and, after some training in timing their eye-movements, habitually.  The first appearance of the handleless image was always a decided surprise to the subject (as also to the writer), and with some eagerness each hastened to verify the phenomenon by new trials.

The two ends (e, e) of the dumb-bell seem to be of the same intensity as in shape 2 when seen in reflex movement.  But there is no vestige whatsoever of a handle.  Two of the subjects stated that for them the place where the handle should have been, appeared of a velvety blackness more intense than the rest of the background.  The writer was not able to make this observation.  It coincides interestingly with that of von Kries,[21] who reports as to the phases of fading after-images, that between the disappearance of the primary image and the appearance of the ‘ghost,’ a moment of the most intense blackness intervenes.  The experiments with the pendulum, however, brought out no ghost.

   [21] Von Kries, J., Zeitschr. f.  Psych, u.  Physiol. d. 
   Sinnesorgane, 1896, XII., S. 88.

We must now enquire why in about half the cases shape 3 is still seen, whereas shape 5 occurs very rarely.  Some of the subjects, among whom is the writer, never saw 5 at all.  We should expect that with the intensity of H sufficiently reduced 4 and 5 would appear with equal frequency, whereas 3 would be seen no oftener than 2; shape 5 appearing when the eye did not, and 4 when it did, move at just the rate of the pendulum.  It is certain that when 4 is seen, the eye has caught just the rate of the pendulum, and that for 3 or 5 it has moved at some other rate.  We have seen above (p. 27) that to move with the pendulum the eye must already move decidedly more slowly than Dodge and Cline find the eye generally to move.  Nothing so reliable in regard to the rate of voluntary eye-movements as these measurements of Dodge and Cline had been published at the time when the experiments on anaesthesia were carried on, and it is perhaps regrettable that in the ‘empirical’ approximation of the natural rate of the eye through 40 deg. the pendulum was set to move so slowly.