ribed can really increase the horse's
acuity in the perception of movements.

Since the light-refracting apparatus of the horse's eye does not offer a
satisfactory explanation for the extraordinary keenness of visual
perception possessed by the Osten horse, we must go a step further and
ask whether it may not perhaps be found in the part immediately
sensitive to light, the retina. That portion really would seem to be
adapted to the perception of movements of minimal extent, and for this
reason: it is more than three times as great in extent as the human
retina, and the horse's retinal images are likewise larger owing to the
position of the nodal point. The cells of the retina that are sensitive
to light, the rods and cones, might therefore be correspondingly larger
than those of the human eye, without thereby making the whole organ less
efficient than the human eye. But the most recent measurements[51] have
shown that the rods and cones of the horse's eye are more minute than
ours. Assuming that, in the case of the horse, as is presumably the case
in human vision, the transition of a stimulus from one retinal cell to
the next already in itself induces a sensation of movement, then the
horse ought indeed be extraordinarily keen in the perception of moving
objects (provided that the horse's more minute cells are packed just as
closely as in the human retina). And besides, there are two specially
adapted areas within the retina of the horse. The "band"
("streifenfoermige Area") which was discovered fifteen years ago by
Chievitz,[52] is a strip of 1 to 1-1/2 millimeters in width, traversing
the entire retina horizontally, and is noteworthy on account of its
structure and probably, too, on account of its greater efficiency. It
may have something to do with the accomplishments of the Osten horse;
but in how far it would be hard to say. The other noteworthy portion of
the horse's retina is the "round area" discovered some four years ago,
located at the rear outer end of the "band", and it is the best-equipped
part of the horse's retina and corresponds to the area of clearest
vision, the yellow spot, in the human eye. But this round area need not
come in for consideration by us, for its location would indicate that it
is used in binocular vision, that is, seeing with both eyes.[53] But in
all our experiments the Osten horse observed only with one eye. That
does not mean, however, that under other circumstances the round area
ma