"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 from its application to man, it is on man that the new experiment should be performed." "Ah, yes," sighed Guy; "we are always tripping up against this impossibility." "Nothing is impossible," I answered. "I am resolved that the experiment shall be performed on man." Guy started, then laughed. "Oh! you are joking," he said. "Not the least in the world. I have even selected the subject." "Eh! well, since you are so determined, you may dissect me when you choose. Only I warn you of difficulties with the tribunals afterwards." "I leave you to settle with them. It is not you, but myself, who is to be the subject; and you must perform the experiment."