The hound was secured, and together we carried the Professor up to his room, where Bennett, who had a medical degree, helped me to dress his torn throat. The sharp teeth had passed dangerously near the carotid artery, and the haemorrhage was serious. In half an hour the danger was past, I had given the patient an injection of morphia, and he had sunk into deep sleep. Then, and only then, were we able to look at each other and to take stock of the situation.
"I think a first-class surgeon should see him," said I.
"For God's sake, no!" cried Bennett. "At present the scandal is confined to our own household. It is safe with us. If it gets beyond these walls it will never stop. Consider his position at the University, his European reputation, the feelings of his daughter."
"Quite so," said Holmes. "I think it may be quite possible to keep the matter to ourselves, and also to prevent its recurrence now that we have a free hand. The key from the watch-chain, Mr. Bennett. Macphail will guard the patient and let us know if there is any change. Let us see what we can find in the Professor's mysterious box."
There was not much, but there was enough—an empty phial, another nearly full, a hypodermic syringe, several letters in a crabbed, foreign hand. The marks on the envelopes showed that they were those which had disturbed the routine of the secretary, and each was dated from the Commercial Road and signed "A. Dorak". They were mere invoices to say that a fresh bottle was being sent to Professor Presbury, or receipts to acknowledge money. There was one other envelope, however, in a more educated hand and bearing the Austrian stamp with the postmark of Prague. "Here we have our material!" cried Holmes, as he tore out the enclosure.
"Honoured Colleague", it ran "Since your esteemed visit I have thought much of your case, and though in your circumstances there are some special reasons for the treatment, I would none the less enjoin caution, as my results have shown that it is not without danger of a kind.
"It is possible that the serum of Anthropoid would have been better. I have, as I explained to you, used black-faced Langur because a specimen was accessible. Langur is, of course, a crawler and climber, while Anthropoid walks erect, and is in all ways nearer.
"I beg you to take every possible precaution that there be no premature revelation of the process. I have one other client in England, and Dorak is my agent for both.
"Weekly reports will oblige.
"Yours with high esteem,
"H. Lowenstein."
Lowenstein! The name brought back to me the memory of some snippet from a newspaper which spoke of an obscure scientist who was striving in some unknown way for the secret of rejuvenescence and the elixir of life. Lowenstein of Prague! Lowenstein with the wondrous strength-giving serum, tabooed by the profession because he refused to reveal its source. In a few words I said what I remembered. Bennett had taken a manual of zoology from the shelves. "'Langur'," he read, "'the great black-faced monkey of the Himalayan slopes, biggest and most human of climbing monkeys.' Many details are added. Well, thanks to you, Mr. Holmes, it is very clear that we have traced the evil to its source."
"The real source," said Holmes, "lies, of course, in that untimely love affair which gave our impetuous Professor the idea that he could only gain his wish by turning himself into a younger man. When one tries to rise above Nature one is liable to fall below it. The highest type of man may revert to the animal if he leaves the straight road of destiny." He sat musing for a little with the phial in his hand, looking at the clear liquid within. "When I have written to this man and told him that I hold him criminally responsible for the poisons which he circulates, we will have no more trouble. But it may recur. Others may find a better way. There is danger there—a very real danger to humanity. Consider, Watson, that the material, the sensual, the worldly would all prolong their worthless lives. The spiritual would not avoid the call to something higher. It would be the survival of the least fit. What sort of cesspool may not our poor world become?" Suddenly the dreamer disappeared, and Holmes, the man of action, sprang from his chair. "I think there is nothing more to be said, Mr. Bennett. The various incidents will now fit themselves easily into the general scheme. The dog, of course, was aware of the change far more quickly than you. His smell would ensure that. It was the monkey, not the Professor, whom Roy attacked, just as it was the monkey who teased Roy. Climbing was a joy to the creature, and it was a mere chance, I take it, that the pastime brought him to the young lady's window. There is an early train to town, Watson, but I think we shall just have time for a cup of tea at the "Chequers" before we catch it."
