all the subjects saw both streaks if the arc of movement was large,
say 40°, and all saw only the correctly localized streak if the arc
was small, say 5°. Arcs of medium length revealed individual
differences between the persons, and these differences, though
modified, persisted throughout the experiments. After the subjects had
become somewhat trained in observation, the falsely localized streak
never appeared without the correctly localized one as well. For the
sake of brevity the word 'streak' is retained, although the appearance
now referred to is that of a series of separate spots of light
arranged in a nearly straight line.

The phenomena are as follows.--(1) If the arc of movement is small, a
short, correctly localized streak is seen extending from the final
fixation-point to the light-spot. It is brightest at the end nearer
the light. (2) If the eye-movement is 40° or more, a streak having a
length of about one third the distance moved through is seen on the
other side of the light from the final fixation-point; while another
streak is seen of the length of the distance moved through, and
extending from the final fixation-point to the light. The first is the
falsely, the second the correctly localized streak. The second, which
is paler than the first, feels as if it appeared a moment later than
this. The brighter end of each streak is the end which adjoins the
luminous spot. (3) Owing to this last fact, it sometimes happens, when
the eye-movement is 40° or a trifle less, that both streaks are seen,
but that the feeling of succession is absent, so that the two streaks
look like one streak which lies (unequally parted) on both sides of
the spot of light. It was observed, in agreement with Schwarz, that
the phenomenon was the same whether the head or the eyes moved. Only
one other point need be noted. It is that the false streak, which
appears in the beginning to dart from the luminous hole, does not