ould find
that this series is identical with the one in which they are grouped
with reference to the form of the blind-spot from the circular up to
the most elongated. (In such a series the marmot takes the place of
honor.)

This exposition is not very satisfactory, however. We cannot be sure
what he means by "keenness of vision" ("scharfaeugigkeit"). Is it
visual acuity in the usual sense of the term (as is said in one of
his passages), or keenness in the perception of the movements of
objects, (this would appear to be his real meaning), or both at the
same time. But whatever the significance he may put into the term,
any such attempt at grouping the lower forms must prove
unsatisfactory from the very start on account of the scant data
which we possess on visual perception in animals. The experiences of
the hunt upon which Koenigshoefer partly bases his view, are entirely
inadequate for such a purpose. This much is certain, that the Osten
horse, in spite of a blind-spot which, though somewhat oval, is by
no means very elongated, possesses an extraordinary acuity in the
perception of movements. Even if the parallelism mentioned by
Koenigshoefer were really shown to exist, it would not explain the
matter until it were also shown in what way keenness of vision is
dependent upon the shape of the blind-spot,--a portion of the eye
which is not immediately operative in the visual sensation at all.]

We can understand also the horse's never-flagging attentiveness when we
recall that self-preservation prompts eternal vigilance over against all
that is going on in the animal's environment. (In the case of Hans,
hunger was at first the motive; later, habit did the work.) Furthermore,
the lower form is not hindered in giving itself over to its
sense-impressions by the play of abstract thought which tends so
strongly to direct inward our psychic energy,--at least, in the case of
the cultured.

Nevertheless, Hans still remains a phenomenon not only in excelling all
his critics in the power of observation, but also in that he is the
first of his species, in fact the first animal, in which this
extraordinary perceptual power has been proven experimentally to be
present. It has long been known[55] that horses could be trained to
respond to cues in the form of slight movements, which remained
unnoticed by the layman, and this fact has been made us