326 Dr.Reuben on Moving Blood-corpuscles within the Retina, 
. The movements were in all directions; in lines straight or 
contorted; generally indicating some divergency from certain 
points or from along certain lines; and only to be traced after 
some practice. 
6. Thus aided, however, it soon became evident that, as long 
as the eye was not shifted, the moving objects kept in each part 
of the field to certain directions, upward along one narrow band, 
downward or obliquely along another, as if confined to particular 
channels or paths. ; 
7. The blue glass showed the movements best; but the eyes 
were not at the time actually directed to the apparent place of 
the sky, but so that the optic axes met in the space seemingly 
snonmied by the moving objects—not more than four feet from 
the eyes. 
8. With this glass, there was no difficulty in converging the 
eyes to this space. The objects appeared so distinct, that the 
vision seemed involuntarily adj t 
8. Yet it was easy to observe that if the eyes were forcibly 
directed to the sky, or if in any way the direction of the axes to 
the apparent field of the shining points was lost, the latter were 
less distinctly perceived; and with media of most colors other 
than the deep blue, were wholly lost. 
e facts can only be reconciled with the hypothesis that the 
lucid lines are quasi-visible traces of the corpuscles of the blo 
moving in vessels. in the retina; and that they were such, I be- 
came convinced during the first observation of them. That the 
blood can be only that of vessels in the retina, becomes certain 
when we rememb 
Bt | OY CES age ee ee ee 
er— 
a.—That these vessels lie in the anterior half-depth of the> — 
transparent retina itself. 
b.—That the vessels of the choroid coat lie behind the retina 
or laterally to it, and imbedded in absorbent or black pigment. 
c.—That in the eye, subsequent to birth, there are no vessels 
other than those in the retina, that lie in the course of the cone 
of rays admitted by the pupil. 
us, these apparently trifling observations acquire at once 
both a physiological and a psychological interest, as showing the 
visual surface and the objects positively impressing it brought, 
a 
f 
certainly, to their extreme limit of contiguity! I have called 
this quasi-vision, because it does not arise from the presence of 
any object the rays from which are brought to foci by the crys- 
talline lens; that is, the case is not one of ordinary vision. Yet 
there is a positive impression on the retina, and of just such kind 
that the mind interprets it into the vision of real, glistening ob- 
jects in the air. The cause is a subjective one (physiologically 
considered); but the perception (so far as the mind is concerned), 
is clearly objective and real. That the phenomenon was not due to 
