" And Lola rapped one (10) with the left paw and five times
with the right. It was evident that she had understood me perfectly!

This gave me confidence, and that day we did additions up to twenty,
all of which were successful. Indeed, the dog showed much interest in
her work, and came to it readily. As a rule ten to fifteen minutes in
the morning, and another quarter of an hour in the afternoon was
lesson-time. As the results were generally successful, I was sometimes
tempted to continue my questions for a little longer, and she would go
on answering until at length she began to sigh--then I knew that she
was tired. And after such extra exertion I would notice the next day
both by the pupils of her eyes and her nervous trembling, that she had
been over-worked--and the thought of it makes me feel ashamed, even to
this day; for, was I not undertaking the whole study for the sake of
animal creation, and to think that I might have been inflicting any
cruelty was unbearable. And, indeed, as time went on, this did not
occur again, for I kept a keener watch. Soon, too, her capabilities
increased, and she was able to fulfil more easily the greater demands
made on her when answering to questions. With regard to decimals and
units, I made a discovery which is, I think, worth stating. The dog did
not look at me, but seemed, on the contrary (on this occasion), much
interested in gnawing the leg of a chair, and I thought she could not
have understood me, or else she would surely have looked up at me. Yet,
she had apparently only done this to cover her confusion--as it were!
Indeed, this was evident from her expression, and she had heard
everything right enough, for she then--and ever after--rapped her
replies without "visualizing"--and I mentally returned thanks to Karl
Krall for the practical advice he had given me, and which had been so
opportune. Rolf rapped with one paw only, as has already been stated;
one was, therefore, obliged at length to put the question to him: "1 or
10?" And Rolf would then say "yes" or "no," as the case might be. This
is confusing for the onlookers, and, as a matter of fact, when I saw
him at Mannheim I never knew for certain what number he had indicated.
But with Krall's method of using alternate hoof or paw, any confusion
or doubt is ruled out.

CONTINUED TUITION

Lola and I had now become to some extent accustomed to each other, and
the daily progress assisted this mutual understanding. I