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 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 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 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 insure 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 have time for a cup of tea at the Chequers before we catch it.”

It is a most singular thing that a problem which was certainly as abstruse and unusual as any which I have faced in my long professional career should have come to me after my retirement, and be brought, as it were, to my very door. It occurred after my withdrawal to my little Sussex home, when I had given myself up entirely to that soothing life of Nature for which I had so often yearned during the long years spent amid the gloom of London. At this period of my life the good Watson had passed almost beyond my ken. An occasional week-end visit was the most that I ever saw of of him. Thus I must act as my own chronicler. Ah! had he but been with me, how much he might have made of so wonderful a happening and of my eventual triumph against every difficulty! As it is, however, I must needs tell my tale in my own plain way, showing by my words each step upon the difficult road which lay before me as I searched for the mystery of the Lion’s Mane.

The Growler and the Masher were waiting for him in the drawing-room of the Hotel Franklin, a small family-hotel near the Trocadero. Mme. Mergy had not yet written to him.

"Oh," he said, "I can trust her! She will hang on to Daubrecq until she is certain."

However, toward the end end of the afternoon, he began to grow impatient and anxious. He was fighting one of those battles - the last, he hoped - in which the least delay might jeopardize everything. If Daubrecq threw Mme. Mergy off the scent, how was he to be caught again? They no longer had weeks or days, but only a few hours, a terribly limited number of hours, in which to repair any mistakes that they might commit.

He saw the proprietor of the hotel and asked him:

"Are you sure that there is no express letter for my two friends?"

"Quite sure, sir."

"Nor for me, M. Nicole?"

"No, sir."

"That's curious," said Lupin. "We were certain that we should hear from Mme. Audran."

Audran was the name under which Clarisse was staying at the hotel.

"But the lady has been," said the proprietor.

"What's that?"

"She came some time ago and, as the gentlemen were not there, left a letter in her room. Didn't the porter tell you?"

Lupin and his friends hurried upstairs. There was a letter on the table.

"Hullo!" said Lupin. "It's been opened! How is that? And why has it een cut about with scissors?"

The letter contained the following lines:

"Daubrecq has spent the week at the Hotel Central. This morning he had his luggage taken to the Gare de --- and telephoned to reserve a berth in the sleeping-car --- for ---

"I do not know when the train starts. But I shall be at the station all the afternoon. Come as soon as you can, all three of you. We will arrange to kidnap him."

"What next?" said the Masher. "At which station? And where's the sleeping-car for? She has cut out just the words we wanted!"

"Yes," said the Growler. "Two snips with the scissors in each place; and the words which we most want are gone. Who ever saw such a thing? Has Mme. Mergy lost her head?"

Lupin did not move. A rush of blood was beating at his temples with such violence that he glued his fists to them and pressed with all his might. His fever returned, burning and riotous, and his will, incensed to the verge of physical suffering, concentrated itself upon that stealthy enemy, which must be controlled then and there, if he himself did not wish to be irretrievably beaten.

He muttered, very calmly:

"Daubrecq has been here."

"Daubrecq!"

"We can't suppose that Mme. Mergy has been amusing herself by cutting out those two words. Daubrecq has been here. Mme. Mergy thought that she was watching him. He was watching her instead."

"How?"

"Doubtless through that hall-porter who did not tell us that Mme. Mergy had been to the hotel, but who must have told Daubrecq. He came. He read the letter. And, by way of getting at us, he contented himself with cutting out the essential words."

"We can find out... we can ask... "