The following morning the secret agent sat in his study immersed in the newspapers. Each contained a circumstantial account of the murder of Dr. Morse, and each, according to its policy, commented thereon. Much was made of the mysterious happenings at Sharsdale and the equally mysterious communications at Eastbury; the police had gone to apprehend Karkowsky at his lodgings, but he was missing.

The Star, true to its enterprising spirit, contained front page reproductions of the three drawings which young Warwick had shown Ashton-Kirk.

"The pictures," said this newspaper, "will in the end be found to contain the solution of the entire matter. What they mean and why the colors varied so is just now a puzzle. The crowned woman and the cross with the different colored strokes are at this stage of the case absolutely without meaning. But the police are working upon this phase of the affair with much interest and zeal; and any hour may bring forth amazing results. Osborne, a talented man from the central office, has the matter in hand; and judging from past performances, he should accomplish wonders."

"Well, there are worse than Osborne," commented Fuller when his employer pointed out the latter passage, "but he'll never set the earth to rocking, at that."

"He has a healthy brain," said Ashton-Kirk, "but he seldom centers it properly. And if his mind is kept constantly between the narrow barriers of police procedure, its possessor cannot hope for moments of inspiration."

The Standard dwelt at great length upon the missing bag and the disappearance of Philip Warwick. The story of the two Japanese convinced this newspaper that with Warwick discovered the case would end there and then.

"There can scarcely be any doubt that it was he whom Messrs. Okiu and Humadi saw leaping over the hedge fence in the moonlight," declared the Standard. "The leather bag which he carried was more than likely the same that Dr. Morse was fumbling with when the servant last saw him in the library. To be sure, the old woman does not definitely state that it was Warwick's voice which she heard later as she sat upon the step. But circumstances fail to point to any other possible person. The house was absolutely secure, except for the street door, and the servant sat in front of that. It would have been impossible for any one to have passed in and she not be aware of it. The young man, Drevenoff, was in his room from first to last; we are sure of this because Miss Corbin saw him go up the stairs before Dr. Morse sent for the servant about the key, and is absolutely certain that he did not come down until after the body was discovered. Warwick, therefore, is the only person unaccounted for; and the fact that a person answering his description, even if only vaguely, was seen stealing away shortly after the time the crime must have been committed, seems almost convincing evidence of his guilt. And that this dimly seen person also carried a hand-bag, the only article learned to be missing, and that Warwick's present whereabouts is unknown, almost clinches the supposition."

Fuller nodded his head at this.

"They make a good case against him," said he. "I'm also of the opinion that Warwick, when found, will tell a mighty illuminating story—if he has the mind."

Ashton-Kirk threw the papers from him with a yawn.

"As usual," said he, "they grasp the obvious and apparently sensational features. The trouble with some of the journals and their staffs, however, is not lack of acuteness; it is the desire to get in on a good story before their rivals—to flame out into broad-faced type which will give the prospective purchaser a blow between the eyes as it lies upon the stand, or allow the newsboys a fine line to fill the streets with. But the real things are not brought forward with such a dramatic rush; they filter gradually through a mass of extraneous matter and their quality appears only to a person seeking an absolutely convincing result."

He pulled off his coat and turned up his sleeves; entering the laboratory, he opened the drawer of a stand and took out the two pieces of glass broken from the front of Dr. Morse's bookcase. Holding these up to the light he said:

"We secured two very satisfactory blood smears under most unpromising conditions. That the clot was not altogether hard was fortunate; and that I was able to take advantage of the fact without accident was doubly so."

Lighting a Bunsen burner he passed the glass once through the flame; then he took a shallow vessel and poured out a quantity of liquid; in this he immersed one of the bits of glass with its dry stain.

"Some sort of a test?" inquired Fuller.

"Yes. This bath of alcohol will fix the smear."

"I see."

Fuller's curiosity prompted him to inquire as to what would follow this fixation; but knowledge of the other's habits of mind forbade this.

"About all that is known of the parasite for which I am going to seek," said Ashton-Kirk as he stood by the tray, watch in hand, "is due in the first place to a French army surgeon named Laveran. After him came the Italian, Marchiafava, the German, Koch, and a number of others. There is a monograph upon the subject by Mannaberg which is most comprehensive."

"What sort of a little beast is it?" asked Fuller.

"A lively, wriggling atom—a unicellular organism, directly upon the border-land between the animal and vegetable kingdoms."

"That sounds very exact and scientific," said the other. "But it means little to me."

"The young specimens of the plasmodia, as this particular germ is styled, develop in the red blood cells; and as they grow they destroy their habitation. I could tell you of interesting changes of color in the blood corpuscles, of the active, joyous dancing of the parasite, and of its multiplication by sporulation. But not now. All this, however, is repeated again and again; and each sporulation of the parasite is usually associated with marked symptoms in the person whose blood it inhabits."

"You speak as though you expected to find some such condition in this," and Fuller nodded toward the blood smear.

"I expect nothing. I am merely about to prove or disprove a suggestion."

At the end of twenty minutes, Ashton-Kirk took the bit of glass from the fixing bath, threw the alcohol into a waste pipe and ran some water into the vessel.

"It will take some ten minutes for the slide to dry," said he. "And in the meantime we shall prepare the next step in the process."

He took down a bottle filled with a dark blue liquid. This he held up to the light that poured in from the window.

"Here," said he, "is the bloodhound upon whom I depend to find and mark the parasite. It bears the rather formidable name in its present state of aqueous methylene-blue, and is in a two per cent. solution. Combined with it is a five per cent. solution of borax. I had a druggist send it in this morning."

This mixture he poured into the small vessel until the bottom was barely covered; then he added water until there was a layer of perhaps one centimeter in thickness, and the blue began to become transparent.

The alcohol had dried off the bit of glass by this time; and Ashton-Kirk took the fragment up with a pair of forceps and dipped it several times into the methylene stain; after this he passed it through clear water until the blue paled to a greenish tinge. Then he took up a white disc of filter paper; placing this upon a stand he laid the glass upon it and carefully dried both sides, much as one would blot ink from a letter sheet.

"This process is what is called staining," said Ashton-Kirk, "and the method I have used is one recommended by Koch; it is somewhat similar to the older one of Mannaberg, but more rapid in result."

Out of a tube he dropped a single gem-like globule of cedar oil upon the blood smear; then he covered it with a small square of glass; upon this in its turn fell a second drop of the oil.

The whole was then placed in position under a microscope and fastened. Then the secret agent brought out the lens. It glittered like a tiny diamond in a huge setting, and Fuller gazed at it fascinated.

"How you can see anything through a glass as small as that I can't understand," said he. "It looks like the point of an awl."

"It is a one-twelfth objective," replied the other, as he screwed the lens firmly down upon the cover glass, and thus embedded it, so to speak, in the globule of cedar oil.

"It is necessary," said he, "that the specimen be observed through the oil because the lens must be brought down directly upon the glass; without the oil the glass would be scratched and the whole thing ruined."

Then he set himself to the close study of what the tiny lens made plain; in a few moments he lifted his head with an exclamation of triumph.

"I have it!" he cried.

"What have you found?" asked Fuller eagerly.

"Evidence," answered Ashton-Kirk, triumphantly, "that will enable me to lay my hand upon the person who searched the library and clothing of Dr. Morse."

"The murderer?"

"Perhaps he is that also—who knows?"

"But," demanded Fuller, "I don't quite understand."

Ashton-Kirk waved his hand toward the microscope, and Fuller applied his eye to it.

"What do you see?" asked the secret agent.

"A pale green circle," answered the other, "and it is crowded with irregularly shaped spots."

"Compare the circle with the dial of a watch and look closely at the point where the six should be."

"Yes," said Fuller.

"What do you see—at a very little distance from the edge?"

"There are some small blue spots; some are dark, the others lighter and more intense."

"That last is my proof," said Ashton-Kirk. Then as Fuller turned upon him a still inquiring look, he added:

"The indications have been that some member of Dr. Morse's household had a hand in his death. The house was secure at all points; it was not possible for any one to gain an entrance after the locking up. You might say: Suppose the criminal had entered the house before the time for locking up and remained concealed until he saw his opportunity? To that I would answer that we would have detected his method of departure. He should have left something unfastened behind him unless he had a confederate in the house. That the doors and windows, in every instance, were fast proves that this must be the case."

Fuller nodded his head.

"That's so," said he.

"Now let us take the members of the household one at a time. Miss Corbin——"

Fuller waved his hand.

"Oh, she's out of it," said he.

"Very well," said Ashton-Kirk, his white teeth showing in a smile. "Then let us take up Nanon. Here we have a severely religious woman—one who evidently detested her employer, but who served him well and had been many years in the family."

"It looks as though we'd have to pass her, too," said Fuller. "There is no reason why she should murder Dr. Morse that I can see."

Again the other smiled.

"In this you agree with the newspapers, at any rate," said he. "None of them have found occasion to associate her with the matter, either."

"I also agree with the papers in the matter of Warwick," said Fuller. "I know that it's best to start without preconceived notions, but I can't help thinking that, if he's not exactly the man, he knows quite a bit about it all."

"That he has unaccountably disappeared is a bad point against him," admitted Ashton-Kirk. "And that some one resembling him was seen stealing away in the night, carrying a hand-bag, is another and most damaging one. However, as you say, it is best not to start with preconceived notions; and until we are sure that the unknown was Warwick, and that the bag he carried was the missing bag, we'd better not accuse him."

There was a pause; the secret agent looked at the stained blood smear for a moment and then continued:

"There is still another person—the fourth and last. This person possessed the marked symptoms of a common complaint—chills followed by fever. To this person I know Dr. Morse gave quinine."

"Well?" asked Fuller, eagerly.

"Chills and fever are indications of malaria—quinine is the invariable remedy for that complaint. And the light blue spots which you see in that smear of blood," pointing to the microscope, "are the germs of that same disease."

For a moment Fuller stood as though transfixed.

"You have the man!" he cried at last. "You have him beyond the shadow of a doubt! To think," in great admiration, "that he should be found out in such an unusual way. Why, it is one of the——" Here he paused, the enthusiasm died from his face, and he added slowly: "But suppose that blood clot was not left upon the drawer pull at the time you think. The man may have been in the library during the afternoon upon a perfectly legitimate errand."

But Ashton-Kirk shook his head.

"No," said he. "It happened last night about the time of the murder. If it had been earlier the blood would have been dry and hard to the core."

"I see," said Fuller. "I recall that you were surprised at its having retained any softness, even at that. But there is something else. If Miss Corbin is sure that Drevenoff did not descend from the third floor, after once going to his room, how do you account for his presence in the library at that time?"

"Miss Corbin was in position to see Drevenoff as he ascended the back stairs. She did not see him descend, and so concluded that he could not have done so. As a matter of fact he could have gained the first floor without any trouble by passing through some unoccupied rooms upon the third floor, and using the front or main staircase."

"Then that's it," declared Fuller. "He came down that way while the old servant was in the kitchen seeing to the coffee, did his work and went back to his room by the same route. But," with a puzzled look upon his face, "what in the world ever drew your attention to Drevenoff in the first place—that is, what made you think it might be his blood upon the handle of the drawer?"

"Do you recall that while I was examining the desk I stopped to listen?"

"Yes, and told me to put out the lights."

"The sound that I heard came from the room in the rear of the library; when I asked you to switch off the lights it was because I wanted to open the door between the two rooms without the knowledge of the person who may have made the sound."

"You saw no one?"

"No. But I heard something like quick footsteps going down the hall, and then the soft closing of the street door."

"By George, I heard that, too," said Fuller, remembering.

"Some one had been in the room in the rear of the library," said Ashton-Kirk. "What I heard in the first place was perhaps some sort of sound made as he was stealing away. Drevenoff was the last person I had seen in the hall, and naturally he was suggested to me as the cause of the sounds."

"But you had told him to go to the police station."

"Told him—yes. But if you will remember, he had not yet gone when we entered the library. He said that the police station was a matter of four blocks; if he had gone at once he would have reached there long before I heard the sound in the back room. I at once went to the 'phone, which I had noticed in the back hall, and called up the station in question. No; he had not yet reached there. Would the sergeant kindly make a private note of when he did? The sergeant would."

"And did he?"

"He whispered it to me as I was leaving the house later. Drevenoff reached the police station less than ten minutes after I called them up—just about the length of time it would take him to get there if it were he who had been in the rear room."

"Ah!"

"The man's actions seemed suspicious, even before I received this apparent verification; also I had not forgotten the intelligence we had gathered concerning his father. So when I came upon the blood clot I naturally had him in mind; the symptoms of malaria and the quinine came back to me, and I at once determined upon this test on the chance that it would turn out as it has."

"I think you have sufficient evidence to have him taken at once." But Ashton-Kirk shook his head.

"It would be enough to hold him on, at any rate," protested Fuller. "And if he's not arrested now, he may escape, and Dr. Morse's murder will go unavenged."

The secret agent took up his big German pipe.

"The murder of Dr. Morse," said he, "is a most frightful crime against society. I am perfectly willing to do what I can to trace the criminal, but don't forget that the important matter with us is another thing entirely."

"You mean the document, or whatever it was, which was stolen by Drevenoff's father?"

"Which may have been stolen by Drevenoff's father. Exactly. The murder of Dr. Morse is only incidental to this." Here the pipe was lighted and heavy clouds of smoke began to rise. "And even though young Drevenoff should prove to be the murderer, I don't think we need fear his attempting to escape."

"No?"

"No. For some little time, at any rate, it will be perfectly safe to give him a free foot; indeed, it may prove to be of great advantage to us to do so. He has not yet found the thing of which he is in search. That is plain. If he had, he would have been off before now. So, for a time at least, it will be highly interesting to watch his movements; for who knows but what it is through him that we are to save the government much embarrassment."

Fuller regarded his employer, the huge pipe and the smoke clouds which rose lazily above both; there was much speculation in his eye.

"You have not lost sight of the Japanese?" said he.

"The Japanese!" Ashton-Kirk took the amber bit from his mouth and his white teeth gleamed as he laughed. "Oh, no! I have not forgotten them. Mr. Okiu and his friend Mr. Humadi interest me exceedingly."