for
him by the very non-critical compiler, Zell[28]--Hans, on the contrary,
has at his service a remarkably small number of associations. For,
besides possessing the powers of any ordinary horse, he recognizes only
a few meager visual signs. To be sure, we find in the literature a horse
that was said to have recognized 1500 signals,[29] but all proof is
lacking and the report is so meager that we cannot discover whether
these signs were auditory or visual.[V]

[Footnote V: The French investigators Vaschide and Rousseau make a
reference to this case, and mistakenly state the number of signals
as 1500 instead of 115[30]. Ettlinger[31] takes over this wrong
figure and makes the additional mistake of assuming that the
reference is to an original investigation made by the two
Frenchmen.]

Having thus disposed of all questions concerning the horse's apparent
feats of reason and memory, let us turn to those in the field of
sensation. We shall begin with vision. That Hans was unable to select
colored pieces of cloth merely upon the basis of color quality, without
reference to their order, was shown in Chapter II. It would, however, be
somewhat hasty to infer color-blindness from this fact, as did
Romanes[32] on the basis of similar unsucessful responses on the part of
a chimpanzee ("Sally" of the London Zooelogical Garden). It is much
easier to explain the failure of the horse than that of the monkey on
the basis of intellectual poverty, a poverty of associative activity. It
presumably can discriminate between the various colors, but it cannot
associate with these their names. The existence of chromatic vision in
the lower forms is by no means as unquestionable as is assumed by
popular thought. Even teleological considerations which are often
brought forward (especially that of the ornamental and protective
coloring of so many animals) can never do more than establish a certain
probability. For definite proof, we need data given by observation (we
have none in this case), or experimental evidence. Such evidence we
have, but it is insufficient in quantity and unfortunately most of it
was obtained under inadequate experimental conditions.[W] We know
nothing regarding chromatic vision in the horse, though we have often
had trained horses which apparently possessed color discrimination. The
earliest report of this kind I find in a work published in the year
1573.[36] Here we read that a number of Germans e