y to do his tasks with any persons who are
sympathetic to him should he know them well enough. It is, however,
difficult to get him to work as long as anyone who is not
sympathetic remains in the room. What he raps out is, of course,
phonetically spelt--just according to how it sounds to him, and we
have not attempted to worry him with orthography! His own original
remarks are delightful."

The dog, Rolf, attained in the course of time to a higher level than
did the horses. This may probably be explained by the fact that dogs
are, as a rule, more continuously in the company of human beings, being
also due to their superior intelligence. Rolf's mode of procedure
consisted in a series of raps given with his fore-paws, similar to
those given by the horses with their hoofs; but Rolf used the same paw
for both decimals and units, so that we had from time to time to
inquire after every number rapped out--'Is it a decimal or a unit?'
Whereupon he would rap 'yes,' or 'no'--as the case might be. The
numbers were then written down and the answers thus obtained.

Rolf's feats of arithmetic, like those performed by the horses,
included finding the square root in the most difficult problems; yet it
was in the matter of spelling answers that he excelled. Indeed, he
seemed to command a particularly rich vocabulary, and applied the same
with the greatest accuracy and continuity, even in long answers. These
replies, when collected in their proper sequence should provide us with
a wealth of insight into an animal's life of feeling. Such a collection
is already extant, but has not yet been made public.

Many of the dog's answers, as well as innumerable debates about him
have been published in the "Mitteilungen der Gesellschaft fuer
Tierpsychologie"[2] ("Communications of the Society for the Study of
Animal Psychology"), while others may be found in the periodical
"Animal Soul."[3]

[2] Published by the committee through the agency of Professor
Ziegler.

[3] Published by Emil Eisell, in Bonn.

Rolf has made frequent public appearances and been subjected to tests
of several hours' duration. These have taken place both in the presence
of his kind and gifted mistress and teacher, and also quite alone with
his examiners. On every occasion of his appearance notes have been
taken as to the procedures, and on one occasion these were even
attested by a Notary. At such times, indeed, suggestions were