But suppose this obedience did not suffice to release me. Suppose
that, in my agony, I prayed you to drive your own sword into my heart
to set me free. Would you do it?"

He hesitated a moment. "That would be a terrible prayer; yet if you
were suffering, and I knew that you must die, I would do even that for
you."

"You have said it," I cried, and leaped to my feet in uncontrollable
excitement. "I have a request to make you, I have a prayer that you
only can fulfil. Swear that you will grant it--swear by all your love
for me, by all the gratitude which you profess, and for which I shall
never claim other return--swear that you will do what I am about to
bid you!"

I saw that Guy was disquieted by my words and manner. Instead of
replying with the bold confidence I had a right to expect, he recoiled
from the revelation that pressed urgently on my lips.

"Take care," he said, "your eyes are glittering as if you had a fever.
Let us stop talking about this till to-morrow."

The upstart boy, thus to dare to patronize me with his foresight and
protection--_me_, who had taught him all he knew, and who was about to
offer him a place on my giddy pinnacle of immortal fame! I was
intensely angry, but succeeded in controlling myself, for I felt that
an untimely explosion of violence might ruin all. I passed my hand
over my eyes, as if to blur the glitter that had alarmed Guy's
scrupulous feebleness, and sat down quietly again.

"The fact is, my dear Guy," I said, "I have been waiting so long for
an opportunity to execute a certain scheme of mine, that I cannot help
being a little excited when this opportunity seems at last within my
reach."

"What kind of a scheme?" asked Guy.

"A scheme for the advancement of the science in which we are both so
interested."

"Oh," said Guy, with an air of relief, "you know how you can rely upon
me for any undertaking in that direction."

"I should think so, especially when it concerns the problem upon which
we have both been so long engaged--the movements of the heart."

"What!" he exclaimed with delight. "You have discovered something new
for that! Shall I ever cease to admire your masterly ingenuity. What
is to be done? You want to send me to Africa to capture a live
rhinoceros? I will set out to-morrow."

"What would be the use! All the information that can be gained by
experiment on the higher mammifers is already ours. Since the problem
derives the greatest part of its interest