of control in trick performances, went over to the other
side as a result of his observations.

There were others who sought for auditory signs. The opinion was
expressed that "Hans was unable to answer the simplest question such as
'What is two plus three?' whenever the questioner's tone of voice
differed from that of the master's." Another put chief stress upon the
changing inflection; furthermore, a "high degree of auditory
sensitivity" was often offered in explanation.

The sense of smell was also made to bear some burdens. With its help,
for instance, Hans was believed to be able to recognize the photograph
of some one present, supposing, of course, that the person had carried
the picture about with him, thus allowing it to be impregnated with his
peculiar personal odor. One even suggested that the heat radiating from
the questioner's body and the electric stimulus conducted underground to
Hans's foot were sufficient explanation for his remarkable feats.

Even the so-called N-rays, of one-day fame, which were supposed to
radiate from the human brain when in activity, were offered as a
solution. A similar thing may have been in the mind of the "natural
philosopher" who even after the publication of the December report,
wrote as follows in one of the journals: "On the basis of most careful
control, I have come to the conclusion, that the brain of the horse
receives the thought-waves which radiate from the brain of his master;
for mental work is, according to the judgment of science, physical
work." Of the same character are the explanations of two others, one of
whom declares that Hans was acting "under the magnetic influence of
man", while the other declared that "hypnotic suggestion is involved",
and, ignoring attested facts, tells us that, "The horse can execute the
commands of another only when the master, with whom it is 'en rapport',
wills that it shall obey." We may close the catalogue of explanations
with one more, which, in spite of its vagueness, found many defenders,
viz: suggestion. Without defining this conception more specifically and
without the slightest notion of the peculiar difficulties which it
involves (L. Loewenfeld in his "Handbuch des Hypnotismus" [Wiesbaden,
1901, pp. 35ff.] cites twenty different definitions of the term given by
as many authors) a critic writes: "The astounding phenomenon of an
animal apparently possessing human reason is to be attributed solely to
suggestion". Having refe