"Since we brought him home, my brother just tosses and gasps for air.
Oh, I think Eulalie and I shall both go mad!"

The soft, pleading voice of Anitra Barrios and her big, appealing brown eyes filled with tears were doubly affecting as, in spite of her own feelings, she placed her hand on that of a somewhat younger girl who had accompanied her to the laboratory.

"We were to have been married next month," sobbed Eulalie Sandoval. "Can't you come and see Jose, Professor Kennedy? There must be something you can do. We fear he is dying—yes, dying."

"Poor little girl!" murmured Anitra, still patting her hand
affectionately, then to us, "You know, Eulalie is the sister of Manuel
Sandoval, who manages the New York business of my brother." She paused.
"Oh, I can't believe it, myself. It's all so strange, so sudden."

For the moment her own grief overwhelmed Anitra, and both sister and sweetheart of Jose Barrios clung to each other.

"What is the trouble?" soothed Craig. "What has happened? How can I help you?"

"Everything was so happy with us," cried Anitra, "until Jose and I came to New York—and—now—" She broke down again.

"Please be calm," encouraged Kennedy. "Tell me everything—anything."

With an effort Anitra began again. "It was last night—quite late—at his office at the foot of Wall Street—he was there alone," she strove to connect her broken thoughts. "Some one—I think it must have been the janitor—called me up at home and said that my brother was very ill. Eulalie was there with me. We hurried down to him. When we got there Jose was on the floor by his desk, unconscious, struggling for breath, just as he is now."

"Did you observe anything peculiar?" queried Kennedy. "Was there anything that might give you a hint of what had happened?"

Anitra Barrios considered. "Nothing," she replied, slowly, "except that the windows were all closed. There was a peculiar odor in the room. I was so excited over Jose, though, that I couldn't tell you just what it was like."

"What did you do?" inquired Craig.

"What could we do, just two girls, all alone? It was late. The streets were deserted. You know how they are down-town at night. We took him home, to the hotel, in a cab, and called the hotel physician, Doctor Scott."

Both girls were again weeping silently in each other's arms. If there was anything that moved Kennedy to action it was distress of this sort. Without a word he rose from his desk, and I followed him. Anitra and Eulalie seemed to understand. Though they said nothing, they looked their gratitude as we four left the laboratory.

On the way down to the hotel Anitra continued to pour out her story in a fragmentary way. Her brother and she, it seemed, had inherited from their father a large sugar-plantation in Santa Clara, the middle province of Cuba.

Jose had not been like many of the planters. He had actually taken hold of the plantation, after the revolution had wrecked it, and had re-established it on modern, scientific lines. Now it was one of the largest independent plantations on the island.

To increase its efficiency, he had later established a New York office to look after the sale of the raw sugar and had placed it in charge of a friend, Manuel Sandoval. A month or so before he had come to New York with his sister to sell the plantation, to get the high price that the boom in sugar had made it worth. It was while he had been negotiating for the sale that he had fallen in love with Eulalie and they had become engaged.

Doctor Scott met us in the sitting-room of the suite which Anitra and her brother occupied, and, as she introduced us, with an anxious glance in the direction of the door of the sick-room, he shook his head gravely, though he did his best to seem encouraging.

"It's a case of poisoning of some kind, I fear," he whispered aside to us, at the first opportunity. "But I can't quite make out just what it is."

We followed the doctor into the room. Eulalie had preceded us and had dropped down on her knees by the bed, passing her little white hand caressingly over the pale and distorted face of Jose.

He was still unconscious, gasping and fighting for breath, his features pinched and skin cold and clammy. Kennedy examined the stricken man carefully, first feeling his pulse. It was barely perceptible, rapid, thready, and irregular. Now and then there were muscular tremblings and convulsive movements of the limbs. Craig moved over to the side of the room away from the two girls, where Doctor Scott was standing.

"Sometimes," I heard the doctor venture, "I think it is aconite, but the symptoms are not quite the same. Besides, I don't see how it could have been administered. There's no mark on him that might have come from a hypodermic, no wound, not even a scratch. He couldn't have swallowed it. Suicide is out of the question. But his nose and throat are terribly swollen and inflamed. It's beyond me."

I tried to recall other cases I had seen. There was one case of Kennedy's in which several deaths had occurred due to aconite. Was this another of that sort? I felt unqualified to judge, where Doctor Scott himself confessed his inability. Kennedy himself said nothing, and from his face I gathered that even he had no clue as yet.

As we left the sick-room, we found that another visitor had arrived and was standing in the sitting-room. It was Manuel Sandoval.

Sandoval was a handsome fellow, tall, straight as an arrow, with bushy dark hair and a mustache which gave him a distinguished appearance. Born in Cuba, he had been educated in the United States, had taken special work in the technology of sugar, knew the game from cane to centrifugal and the ship to the sugar trust. He was quite as much a scientist as a business man.

He and Eulalie talked for a moment in low tones in Cuban Spanish, but it needed only to watch his eyes to guess where his heart was. He seemed to fairly devour every move that Anitra made about the apartment.

A few minutes later the door opened again and a striking-looking man entered. He was a bit older than Sandoval, but still young. As he entered he bowed to Sandoval and Eulalie but greeted Anitra warmly.

"Mr. Burton Page," introduced Anitra, turning to us quickly, with just the trace of a flush on her face. "Mr. Page has been putting my brother in touch with people in New York who are interested in Cuban sugar-plantations." A call from Doctor Scott for some help took both girls into the sick-room for a moment.

"Is Barrios any better?" asked Page, turning to Sandoval.

Sandoval shook his head in the negative, but said nothing. One could not help observing that there seemed to be a sort of antipathy between the two, and I saw that Craig was observing them both closely.

Page was a typical, breezy Westerner, who had first drifted to New York as a mining promoter. Prom that he had gone into selling ranches, and, by natural stages, into the promotion of almost anything in the universe.

Sugar being at the time uppermost in the mind of the "Street," Page was naturally to be found crammed with facts about that staple. One could not help being interested in studying a man of his type, as long as one kept his grip on his pocket-book. For he was a veritable pied piper when it came to enticing dollars to follow him, and in his promotions he had the reputation of having amassed an impressive pile of dollars himself.

No important change in the condition of Barrios had taken place, except that he was a trifle more exhausted, and Doctor Scott administered a stimulant. Kennedy, who was eager to take up the investigation of the case on the outside in the hope of discovering something that might be dignified into being a clue, excused himself, with a nod to Anitra to follow into the hall.

"I may look over the office?" Craig ventured when we were alone with her.

"Surely," she replied, frankly, opening her handbag which was lying on a table near the door. "I have an equal right in the business with my brother. Here are the keys. The office has been closed to-day."

Kennedy took the keys, promising to let her know the moment he discovered anything important, and we hurried directly down-town.

The office of the Barrios Company was at the foot of Wall Street, where the business of importing touched on the financial district. From the window one could see freighters unloading their cargoes at the docks. In the other direction, capital to the billions was represented. But in all that interesting neighborhood nothing just at present could surpass the mystery of what had taken place in the lonely little office late the night before.

Kennedy passed the rail that shut the outer office off from a sort of reception space. He glanced about at the safe, the books, papers, and letter-files. It would take an accountant and an investigator days, perhaps weeks, to trace out anything in them, if indeed it were worth while at all.

Two glass doors opened at one end to two smaller private offices, one belonging evidently to Sandoval, the other to Barrios. What theory Craig formed I could not guess, but as he tiptoed from the hall door, past the rail, to the door of Jose's office, I could see that first of all he was trying to discover whether it was possible to enter the outer office and reach Jose's door unseen and unheard by any one sitting at the desk inside. Apparently it was easily possible, and he paused a moment to consider what good that knowledge might do.

As he did so his eye rested on the floor. A few feet away stood one of the modern "sanitary" desks. In this case the legs of the desk raised the desk high enough from the floor so that one could at least see where the cleaning-woman had left a small pile of unsanitary dust near the wall.

Suddenly Kennedy bent down and poked something out of the pile of dust. There on the floor was an empty shell of a cartridge. Kennedy picked it up and looked at it curiously.

What did it mean? I recalled that Doctor Scott had particularly said that Barrios had not been wounded.

Still regarding the cartridge shell, Kennedy sat down at the desk of
Barrios.

Looking for a piece of paper in which to wrap the shell, he pulled out the middle drawer of the desk. In a back corner was a package of letters, neatly tied. We glanced at them. The envelopes bore the name of Jose Barrios and were in the handwriting of a woman. Some were postmarked Cuba; others, later, New York. Kennedy opened one of them.

I could not restrain an exclamation of astonishment. I had expected that they were from Eulalie Sandoval. But they were signed by a name that we had not heard—Teresa de Leon!

Hastily Kennedy read through the open letter. Its tone seemed to be that of a threat. One sentence I recall was, "I would follow you anywhere—I'll make you want me."

One after another Kennedy ran through them. All were vague and veiled, as though the writer wished by some circumlocution to convey an idea that would not be apparent to some third, inquisitive party.

What was back of it all? Had Jose been making love to another woman at the same time that he was engaged to Eulalie Sandoval? As far as the contents of the letters went there was nothing to show that he had done anything wrong. The mystery of the "other woman" only served to deepen the mystery of what little we already knew.

Craig dropped the letters into his pocket along with the shell, and walked around into the office of Sandoval. I followed him. Quickly he made a search, but it did not seem to net him anything.

Meanwhile I had been regarding a queer-looking instrument that stood on a flat table against one wall. It seemed to consist of a standard on each end of which was fastened a disk, besides several other arrangements the purpose of which I had not the slightest idea. Between the two ends rested a glass tube of some liquid. At one end was a lamp; the other was fitted with an eyepiece like a telescope. Beside the instrument on the table lay some more glass-capped tubes and strewn about were samples of raw sugar.

"It is a saccharimeter," explained Kennedy, also looking at it, "an instrument used to detect the amount of sugar held in solution, a form of the polariscope. We won't go into the science of it now. It's rather abstruse."

He was about to turn back into the outer office when an idea seemed to occur to him. He took the cartridge from his pocket and carefully scraped off what he could of the powder that still adhered to the outer rim. It was just a bit, but he dissolved it in some liquid from a bottle on the table, filled one of the clean glass tubes, capped the open end, and placed this tube in the saccharimeter where the first one I noticed had been.

Carefully he lighted the lamp, then squinted through the eyepiece at the tube of liquid containing what he had derived from the cartridge. He made some adjustments, and as he did so his face indicated that at last he began to see something dimly. The saccharimeter had opened the first rift in the haze that surrounded the case.

"I think I know what we have here," he said, briefly, rising and placing the tube and its contents in his pocket with the other things he had discovered. "Of course it is only a hint. This instrument won't tell me finally. But it is worth following up."

With a final glance about to make sure that we had overlooked nothing,
Kennedy closed and locked the outside door.

"I'm going directly up to the laboratory, Walter," decided Kennedy. "Meanwhile you can help me very much if you will look up this Teresa de Leon. I noticed that the New York letters were written on the stationery of the Pan-America Hotel. Get what you can. I leave it to you. And if you can find out anything about the others, so much the better. I'll see you as soon as you finish."

It was rather a large contract. If the story had reached the newspaper stage, I should have known how to go about it. For there is no detective agency in the world like the Star, and even on the slender basis that we had, with a flock of reporters deployed at every point in the city, with telephones, wires, and cables busily engaged, I might have gathered priceless information in a few hours. But, as it was, whatever was to be got must be got by me alone.

I found Teresa de Leon registered at the Pan-America, as Craig had surmised. Such inquiries as I was able to make about the hotel did not show a trace of reason for believing that Jose Barrios had been numbered among her visitors. While that proved nothing as to the relations of the two, it was at least reassuring as far as Anitra and Eulalie were concerned, and, after all, as in such cases, this was their story.

Not having been able to learn much about the lady, I decided finally to send up my card, and to my satisfaction she sent back word that she would receive me in the parlor of the hotel.

Teresa de Leon proved to be a really striking type of Latin-American beauty. She was no longer young, but there was an elusiveness about her personality that made a more fascinating study than youth. I felt that with such a woman directness might be more of a surprise than subtlety.

"I suppose you know that Senor Barrios is very seriously ill?" I ventured, in answer to her inquiring gaze that played from my card to my face.

For a fleeting instant she looked startled. Yet she betrayed nothing as to whether it was fear or surprise.

"I have called his office several times," she replied, "but no one answered. Even Senor Sandoval was not there."

I felt that she was countering as cleverly as I might lead. "Then you know Mr. Sandoval also?" I asked, adding, "and Mr. Page?"

"I have known Senor Barrios a long time in Cuba," she answered, "and the others, too—here."

There was something evasive about her answers. She was trying to say neither too much nor too little. She left one in doubt whether she was trying to shield herself or to involve another. Though we chatted several minutes, I could gain nothing that would lead me to judge how intimately she knew Barrios. Except that she knew Sandoval and Page, her conversation might have been a replica of the letters we had discovered. Even when she hinted politely, but finally, that the talk was over she left me in doubt even whether she was an adventuress. The woman was an enigma. Had revenge or jealousy brought her to New York, or was she merely a tool in the hands of another?

I was not ready to return to Kennedy merely with another unanswered question, and I determined to stop again at the hotel where Barrios and his sister lived, in the hope of picking up something there.

The clerk at the desk told me that no one had called since we had been there, adding: "Except the tall gentleman, who came back. I think Senorita Barrios came down and met him in the tea-room."

Wondering whether it was Page or Sandoval the clerk meant, I sauntered down the corridor past the door of the tea-room. It was Page with whom Anitra was talking. There was no way in which I could hear what was said, although Page was very earnest and Anitra showed plainly that she was anxious to return to the sick-room up-stairs.

As I watched, I took good care that I should not be seen. It was well that I did, for once when I looked about I saw that some one else in another doorway was watching them, too, so intently that he did not see me. It was Sandoval. Jealousy of Page was written in every line of his face.

Studying the three, while I could not escape the rivalry of the two men, I was unable to see now or recollect anything that had happened which would convey even an inkling of her feelings toward them. Yet I was convinced that that way lay a problem quite as important as relations between the other triangle of Eulalie, Teresa, and Barrios. I was not psychologist enough to deal with either triangle. There was something that distinctly called for the higher mathematics of Kennedy.

Determined not to return to him entirely empty-mouthed, I thought it would be a good opportunity to see Eulalie alone, and hurried to the elevator, which whisked me up to the Barrios apartment.

Doctor Scott had not left his patient, though he seemed to realize that
Eulalie was a most efficient nurse.

"No change," whispered the doctor, "except that he is reaching a crisis."

Interested as I was in the patient, it had been for the purpose of seeing Eulalie that I had come, and I was glad when Doctor Scott left us a moment.

"Has Mr. Kennedy found out anything yet?" she asked, in a tremulous whisper.

"I think he is on the right track now," I encouraged. "Has anything happened here? Remember—it is quite as important that you should tell him all as it is for him to tell you."

She looked at me a moment, then drew from a fold of her waist a yellow paper. It was a telegram. I took it and read:

Beware of Teresa de Leon, Hotel Pan-America.

A FRIEND.

"You know her?" I asked, folding the telegram, but not returning it.

Eulalie looked at me frankly and shook her head. "I have no idea who she is."

"Or of who sent the telegram?"

"None at all."

"When did you receive it?"

"Only a few minutes ago."

Here was another mystery. Who had sent the anonymous telegram to Eulalie so soon after it had been evident that Kennedy had entered the case? What was its purpose?

"I may keep this?" I asked, indicating the telegram.

"I was about to send it to Professor Kennedy," she replied. "Oh, I hope he will find something Won't you go to him and tell him to hurry?"

I needed no urging, not only for her sake, but also because I did not wish to be seen or to have the receipt of the telegram by Kennedy known so soon.

In the hotel I stopped only long enough to see that Anitra was now hurrying toward the elevator, eager to get back to her brother and oblivious to every one around. What had become of Page and the sinister watcher whom he had not seen I did not know, nor did I have time to find out.

A few moments later I rejoined Kennedy at the laboratory. He was still immersed in work, and, scarcely stopping, nodded to me to tell what I had discovered. He listened with interest until I came to the receipt of the anonymous telegram.

"Did you get it?" he asked, eagerly.

He almost seized it from my hands as I pulled it out of my pocket and studied it intently.

"Strange," he muttered. "Any of them might have sent it."

"Have you discovered anything?" I asked, for I had been watching him, consumed by curiosity, as I told my story. "Do you know yet how the thing was done?"

"I think I do," he replied, abstractedly.

"How was it?" I prompted, for his mind was now on the telegram.

"A poison-gas pistol," he resumed, coming back to the work he had just been doing. "Instead of bullets, this pistol used cartridges charged with some deadly powder. It might have been something like the anesthetic pistol devised by the police authorities in Paris some years ago when the motor bandits were operating."

"But who could have used it?" I asked.

Kennedy did not answer directly. Either he was not quite sure yet or did not feel that the time was ripe to hazard a theory. "In this case," he continued, after a moment's thought, "I shouldn't be surprised if even the wielder of the pistol probably wore a mask, doubly effective, for disguise and to protect the wielder from the fumes that were to overcome the victim."

"You have no idea who it was?" I reiterated.

Before Kennedy could answer there came a violent ring at the laboratory bell, and I hurried to the door. It was one of the bell-boys from the hotel where the Barrioses had their apartment, with a message for Kennedy.

Craig tore it open and read it hurriedly. "From Doctor Scott," he said, briefly, in answer to my anxious query. "Barrios is dead."

Even though I had been prepared for the news by my last visit, death came as a shock, as it always does. I had felt all along that Kennedy had been called in too late to do anything to save Barrios, but I had been hoping against hope. But I knew that it was not too late to catch the criminal who had done the dastardly, heartless deed. A few hours and perhaps all clues might have been covered up. But there is always something that goes wrong with crime, always some point where murder cannot be covered up. I think if people could only be got to realize it, as my experience both on the Star and with Kennedy have impressed it on me, murder would become a lost art.

Without another word Kennedy seized his hat and together we hurried to the hotel.

We found Anitra crying softly to herself, while near her sat Eulalie, tearless, stunned by the blow, broken-hearted. In the realization of the tragedy everything had been forgotten, even the mysterious anonymous telegram signed, Judas-like, "A Friend."

Sandoval, we learned, had been there when the end came, and had now gone out to make what arrangements were necessary. I had nothing against the man, but I could not help feeling that, now that the business was all Anitra's, might he not be the one to profit most by the death? The fact was that Kennedy had expressed so little opinion on the case so far that I might be pardoned for suspecting any one—even Teresa de Leon, who must have seen Jose slipping away from her in spite of her pursuit, whatever actuated it.

It was while I was in the midst of these fruitless speculations that
Doctor Scott beckoned us outside, and we withdrew quietly.

"I don't know that there is anything more that I can do," he remarked, "but I promised Senor Sandoval that I would stay here until he came back. He begged me to, seems scarcely to know how to do enough to comfort his sister and Senorita Barrios."

I listened to the doctor keenly. Was it possible that Sandoval had one of those Jekyll-Hyde natures which seem to be so common in some of us? Had his better nature yielded to his worse? To my mind that has often been an explanation of crime, never an adequate defense.

Kennedy was about to say something when the elevator door down the hall opened. I expected that it was Sandoval returning, but it was Burton Page.

"They told me you were here," he said, greeting us. "I have been looking all over for you, down at your laboratory and at your apartment. Would you mind stepping down around the bend in the hall?"

We excused ourselves from Doctor Scott, wondering what Page had to reveal.

"I knew Sandoval had not returned," he began as soon as we were out of ear-shot of the doctor, "and I don't want to see him—again—not after what happened this afternoon. The man is crazy." We had reached an alcove and sank down into a soft settee.

"Why, what was that?" I asked, recalling the look of hate on the man's face as he had watched Page talking to Anitra in the tea-room.

"I'm giving you this for what it may be worth," began Page, turning from me to Kennedy. "Down in the lobby this afternoon, after you had been gone some time, I happened to run into Sandoval. He almost seized hold of me. 'You have been at the office,' he said. 'You've been rummaging around there.' Well, I denied it flatly. 'Who took those letters?' he shot back at me. All I could do was to look at him. 'I don't know about any letters. What letters?' I asked. Oh, he's a queer fellow all right. I thought he was going to kill me by the black look he gave me. He cooled down a bit, but I didn't wait for any apology. The best thing to do with these hot-headed people is to cut out and let them alone."

"How do you account for his strange actions?" asked Kennedy. "Have you ever heard anything more that he did?"

Page shrugged his shoulders as if in doubt whether to say anything, then decided quickly. "The other day I heard Barrios and Sandoval in the office. They were quite excited. Barrios was talking loudly. I didn't know at first what it was all about. But I soon found out. Sandoval had gone to him, as the head of the family, following their custom, I believe, to ask whether he might seek to win Anitra."

"Have you ever heard of Teresa de Leon?" interrupted Kennedy suddenly.

Page looked at him and hesitated. "There's some scandal, there, I'm afraid," he nodded, combining his answers. "I heard Sandoval say something about her to Barrios that day—warn him against something. That was when the argument was heated. It seemed to make Barrios angry. Sandoval said something about Barrios refusing to let him court Anitra while at the same time Barrios was engaged to Eulalie. Barrios retorted that the cases were different. He said he had decided that Anitra was going to marry an American millionaire."

There could be no doubt about how Page himself interpreted the remark.
It was evident that he took it to mean himself.

"Sandoval had warned against this De Leon?" asked Kennedy, evidently having in mind the anonymous telegram.

"Something—I don't know what it was all about," returned Page, then added, in a burst of confidence: "I never heard of the lady until she came to New York and introduced herself to me. For a time she was interesting. But I'm too old for that sort of thing. Besides, she always impressed me as though she had some ulterior motive, as though she was trying to get at something through me. I cut it all out."

Kennedy nodded, but for a moment said nothing.

"I think I'll be getting out," remarked Page, with a half smile. "I don't want a knife in the back. I thought you ought to know all this, though. And if I hear anything else I'll let you know."

Kennedy thanked him and together we rode down in the next elevator, parting with Page at the hotel entrance.

It was still early in the evening, and Kennedy had no intention now of wasting a moment. He beckoned for a cab and directed the man to drive immediately to the Pan-America.

This time Teresa de Leon was plainly prepared for a visit, though I am not sure that she was prepared to receive two visitors.

"I believe you were acquainted with Senior Barrios, who died to-night?" opened Kennedy, after I had introduced him.

"He was acquainted with me," she corrected, with a purr in her voice that suggested claws.

"You were not married to him," shot out Kennedy; then before she could reply, "nor even engaged."

"He had known me a long time. We were intimate—"

"Friends," interrupted Kennedy, leaving no doubt as to the meaning of his emphasis.

She colored. It was evident that, at least to her, it was more than friendship.

"Senor Sandoval says," romanced Kennedy, in true detective style, "that you wrote—"

It was her turn to interrupt. "If Senor Sandoval says anything against me, he tells what is not—the truth."

In spite of Kennedy's grilling she was still mistress of herself.

"You introduced yourself to Burton Page, and—"

"You had better remember your own proverb," she retorted. "Don't believe anything you hear and only half you see."

Kennedy snapped down the yellow telegram before her. It was a dramatic moment. The woman did not flinch at the anonymous implication. Straight into Kennedy's eyes she shot a penetrating glance.

"Watch both of THEM," she replied, shortly, then turned and deliberately swept out of the hotel parlor as though daring us to go as far as we cared.

"I think we have started forces working for us," remarked Kennedy, coolly consulting his watch. "For the present at least let us retire to the laboratory. Some one will make a move. My game is to play one against the other—until the real one breaks."

We had scarcely switched on the lights and Kennedy was checking over the results he had obtained during his afternoon's investigations, when the door was flung open and a man dashed in on us unexpectedly. It was Sandoval, and as he advanced furiously at Kennedy I more than feared that Page's idea was correct.

"It was you, Kennedy," he hissed, "who took those letters from Jose's desk. It is you—or Page back of you—who are trying to connect me with that woman, De Leon. But let me tell you—"

A sharp click back of Sandoval caused him to cut short the remark and look about apprehensively. Kennedy's finger, sliding along the edge of the laboratory table, had merely found an electric button by which he could snap the lock on the door.

"We are two to one," returned Kennedy, nonchalantly. "That was nothing but the lock on the door closing. Mr. Jameson has a revolver in the top drawer of his desk over there. You will pardon me if I do a little telephoning—through the central office of the detective bureau? Some of our friends may not be overanxious to come here, and it may be necessary to compel their attendance."

Sandoval subsided into a sullen silence as Kennedy made arrangements to have Burton Page, Anitra, Eulalie, and Teresa de Leon hurried to us at once.

There was nothing for me to do but watch Sandoval as Kennedy prepared a little instrument with a scale and dial upon which rested an indicator resembling a watch hand, something like the new horizontal clocks which have only one hand to register seconds, minutes, and hours. In them, like a thermometer held sidewise, the hand moves along from zero to twenty-four. In this instrument a little needle did the same thing. Pairs of little wire-like strings ran to the instrument.

Kennedy had finished adjusting another instrument which was much like the saccharimeter, only more complicated, when the racing of an engine outside announced the arrival of the party in one of the police department cars.

Between us, Craig and I lost no time in disposing the visitors so that each was in possession of a pair of the wire-like strings, and then disdaining to explain why he had gathered them together so unceremoniously, Kennedy turned and finished adjusting the other apparatus.

"Most people regard light, so abundant, so necessary, so free as a matter of course," he remarked, contemplatively. "Not one person in ten thousand ever thinks of its mysterious nature or ever attempts to investigate it. In fact, most of us are in utter darkness as to light."

He paused, tapped the machine and went on, "This is a polarimeter—a simple polariscope—a step beyond the saccharimeter," he explained, with a nod at Sandoval. "It detects differences of structure in substances not visible in ordinary light.

"Light is polarized in several ways—by reflection, by transmission, but most commonly through what I have here, a prism of calcite, or Iceland spar, commonly called a Nicol prism. Light fully polarized consists of vibrations transverse to the direction of the ray, all in one plane. Ordinary light has transverse vibrations in all planes. Certain substances, due to their molecular structure, are transparent to vibrations in one plane, but opaque to those at right angles.

"Here we have," he explained, tapping the parts in order, "a source of light, passing in through this aperture, here a Nicol polarizer, next a liquid to be examined in a glass-capped tube; here on this other side an arrangement of quartz plates with rotary power which I will explain in a moment, next an analyzer, and finally the aperture for the eye of an observer."

Kennedy adjusted the glass tube containing the liquid which bore the substance scraped from the cartridge—he had picked up in the office of Jose. "Look through the eyepiece, Walter," he directed.

The field appeared halved. He made an adjustment and at once the field of vision appeared wholly the same tint. When he removed the tube it was dark.

"If a liquid has not what we call rotary power both halves of the double disk appear of the same tint," he explained. "If it has rotary power, the halves appear of different tints and the degree of rotation is measured by the alteration of thickness of this double quartz plate necessary to counteract it. It is, as I told Mr. Jameson early to-day, a rather abstruse subject, this of polarized light. I shall not bore you with it, but I think you will see in a moment why it is necessary, perhaps why some one who knew thought it would never be used.

"What I am getting at now is that some substances with the same chemical formula rotate polarized light to the right, are dextro-rotary, as, for instance, what is known as dextrose. Others rotate it to the left, are levo-rotary, as the substance called levose. Both of them are glucose. So there are substances which give the same chemical reactions which can only be distinguished by their being left or right rotary."

Craig took a bit of crystalline powder and dissolved it in ether. Then he added some strong sulphuric acid. The liquid turned yellow, then slowly a bright scarlet. Beside the first he repeated the operation with another similar-looking powder, with the identical result.

"Both of those," he remarked, holding up the vials, "were samples of pure veratrine, but obtained from different sources. You see the brilliant reaction—unmistakable. But it makes all the difference in the world in this case what was the source of the veratrine. It may mean the guilt or innocence of one of you."

He paused, to let the significance of his remark sink in. "Veratrine," he resumed, "is a form of hellebore, known to gardeners for its fatal effect on insects. There are white and green hellebore, Veratrum alba and Veratrum viride. It is the pure alkaloid, or rather one of them, that we have to deal with here—veratrine.

"There are various sources of veratrine. For instance, there is the veratrine that may be derived from the sabadilla seeds which grow in the West Indies and Mexico. It is used, I am informed, by the Germans in their lachrymatory and asphyxiating bombs."

The mention of the West Indies brought, like a flash, to my mind
Sandoval and Senorita de Leon.

"Then, too," continued Kennedy, "there is a plant out in our own Western country, of which you may have heard, known as the death camas, very fatal to cattle when they eat it. The active principle in this is also veratrine."

I began to see what Kennedy was driving at. If it were veratrine derived from death camas it would point toward Page.

"Abderhalden, the great German physiological chemist, has discovered that substances that once get into the blood produce specific ferments. Not long ago, in a case, I showed it by the use of dialyzing membranes. But Abderhalden has found that the polariscope can show it also. And in this case only the polariscope can show what chemistry cannot show when we reach the point of testing Senor Barrios's blood—if that becomes necessary."

It was plain that Kennedy was confident. "There are other sources of drugs of the nature used in this case to asphyxiate and kill, but the active principle of all is veratrine. The point is, veratrine from what source? The sabadilla is dextro-rotary; the death camas is levo-rotary. Which is it here?"

As I tried to figure out the ramifications of the case, I could see that it was a cruel situation for one or the other of the girls. Was one of her lovers the murderer of Anitra's brother? Or was her own brother the murderer of Eulalie's lover? I looked at the faces before me, now tensely watching Kennedy, forgetful of the wire-like strings which they held in their hands. I studied Teresa de Leon intently for a while. She was still the enigma which she had been the first time I saw her.

Kennedy paused long enough to look through the eyepiece again as if to reassure himself finally that he was right. There was a tantalizing suspense as we waited for the verdict of science on this intensely human tragedy. Then he turned to the queer instrument over which the needle-hand was moving.

"Though some scientists would call this merely a sensitive form of galvanometer," he remarked, "it is, to me, more than that. It registers feelings, emotions. It has been registering your own every moment that I have been talking.

"But most of all it registers the grand passion. I might even call it a love meter. Love might seem to be a subject which could not be investigated. But even love can be attributed to electrical forces, or, perhaps better, is expressed by the generation of an electric current, as though the attraction between men and women were the giving off of electrons or radiations of one to the other. I have seen this galvanometer stationary during the ordinary meeting of men and women, yet exhibit all sorts of strange vibrations when true lovers meet."

Not used to Kennedy's peculiar methods, they were now on guard, ignorant of the fact that that alone was sufficient to corroborate unescapably any evidence they had already given of their feelings toward each other.

Kennedy passed lightly over the torn and bleeding heart of Eulalie. But, much as he disliked to do so, he could not so quickly pass Anitra. In spite of her grief, I could see that she was striving to control herself. A quick blush suffused her face and her breath came and went faster.

"This record," went on Kennedy, lowering his voice, "tells me that two men are in love with Anitra Barrios. I will not say which exhibits the deeper, truer passion. You shall see for yourself in a moment. But, more than that, it tells me which of the two she cares for most—a secret her heart would never permit her lips to disclose. Nor will I disclose it.

"One of them, with supreme egotism, was so sure that he would win her heart that he plotted this murder of her brother so that she would have the whole estate to bring to him—a terrible price for a dowry. My love meter tells me, however, that Anitra has something to say about it yet. She does not love this man.

"As for Teresa de Leon, it was jealousy that impelled her to follow Jose Barrios from Cuba to New York. The murderer, in his scheming, knew it, saw a chance to use her, to encourage her, perhaps throw suspicion on her, if necessary. When I came uncomfortably close to him he even sent an anonymous telegram that might point toward her. It was sent by the same person who stole in Barrios's office and shot him with an asphyxiating pistol which discharged a fatal quantity of pure veratrine full at him.

"My love meter, in registering hidden emotions, supplements what the polarimeter tells me. It was the levo-rotary veratrine of the fatal death camas which you used, Page," concluded Craig, as again the electric attachment clicked shut the lock on the laboratory door.