On the Trail of a Lunar Crime, John Carstairs, the Botanical Detective,

Proves That a Moonman's Meat May Be an Earthman's Poison!

CHAPTER I

Cry in the Lunar Night

"JOHN, John, wake up!" Vera Dorn screamed, pounding on the door of Carstairs' sleeping turret. "The wobblies have broken loose!"

The Curator of the Interplanetary Botanical Gardens stirred, yawned, turned over and buried his head in the bedclothes. "Ahhhh—" he sighed.

"John, let me in! Open the door! The wobblies—"

Carstairs leapt up in consternation, throwing back the bedclothes so violently that they wrapped themselves around his long legs and sent him sprawling. Shivering, he groaned, rolled over and struggled to a sitting position.

"Take it easy, Vera," he muttered, knuckling sleep from his eyelids. "The blasted things aren't flesh-eaters."

"Oh, but, darling, if we should lose them! Our rarest specimens, walking around loose! Can you blame me for getting excited?"

"No, I suppose not," Carstairs grunted. "Open the door yourself. It isn't locked." The door opened a crack, and the pale face of John Carstairs' attractive, coppery-haired secretary came into view. Wrapping the bedclothes tightly around his rangy bulk, Carstairs arose and crossed to the window. When he pulled up the shade a glint of Earthlight from the Lunar Apennines grazed his pupils, dazzling him. He blinked and stared out at the towering peaks which he had been contemplating with awe for several days now.

Vera was sitting on the edge of the bed when he turned, her hands clasped around her knees.

"It will be a shock to Gleason," she said. "One of them came into my room and climbed out the window. I encountered another in the corridor. When I tried to catch it, it hurled a nettle at me. It's still here, in my shoulder."

She turned and bared a portion of her right shoulder. Half-buried in her flesh was a huge, downy nettle. It was strawberry-colored, and five or six inches in diameter. It brought a shiver to Carstairs' spine.

"We'll get it out," he said. "They are loathsome creatures, but worth their weight in platinum."

"You don't seem very upset about losing them," Vera retorted. "They're probably streaking back to the mountains by now."

Carstairs shrugged. "We're Gleason's guests, aren't we? We're spending the weekend with him. The right kind of host doesn't let his guests down. If I'm any judge of character, he won't rest until he's tracked down some more specimens for us."

VERA DORN'S freckled face crimsoned with indignation. "John Carstairs, you're the most cynical, ungrateful person I've ever known. Gleason is an extremely wealthy man. He doesn't have to collect specimens for you."

"He's a good egg," Carstairs grunted. "But vain. Endowing our lunar expeditions and collecting for us puffs him out like a kid's toy balloon. He likes to pose as a scientific big shot. If I had a glassite-walled palace on the moon, decked out with seven black plastic bathrooms, I'd forget about science with a capital S. I'd just be myself."

"What makes you think a wealthy man can't be a humble soldier in the army of science?" Vera flared.

"Heck, we're not fighting anything," Carstairs snorted. "Am I a soldier? All I do is collect unhealthy looking plants, and hold down a dull job on Earth. Utterly nightmarish plants, from `glowing Venus to Neptune's chill domain'—to quote from a book of bum poems I once read."

"John, what are you driving at?"

"Well, do our expeditions save human lives? Is our work really important? Vera, I'm just a tired old man killing a dull weekend with an elderly playboy in his pleasure palace on the moon. If he hadn't sent me a space-o-gram telling me he had an extraordinary new specimen, and would I call for it, I'd be killing a duller one on Earth. Oh, heck."

"You got up on the wrong side of the bed, all right," Vera sneered. "Old man, indeed! You're a few hours past twenty-eight, on account of this is your birthday. But you're not so old, and all you need to pep you up is a nice, juicy, murder."

She wrinkled her nose. "You're just disgruntled because you can't help the New York police department crack down on the criminal element. You're as sore as the dickens because you can't neglect your research work and go rushing around like a turkey with its neck stretched out for the chopping block." Carstairs gnawed at his underlip and glared at the attractive university graduate who had wangled a job for herself at the Interplanetary Botanical Gardens solely on her nerve. Bitterly Carstairs recalled that she had walked into his office on a rainy Sunday, pretending to be a research botanist of established reputation. Actually she had merely majored in botany at college, and had the softest eyes.

"You're a botanist eight days out of seven," he flung at her. "But right now I'm fed up. Fed up, you hear?"

"But, John—"

"All right, wobblies are rare, wobblies are valuable. And Gleason is a resourceful collector. We didn't even know wobblies existed on Luna until he hoisted three adult specimens out of a mountain crevice, and sent me that space-o-gram. I was elated at first, but it's worn off. I'm bored, peeved, and if we've lost them, I just don't give a Neptunian peso."

Vera Dorn's lips tightened ominously. "Botanical Detective John Carstairs is going to eat crow," she said.

"He's going to apologize to the most gracious host a man ever had for putting those valuable specimens in a fragile glass herbarium. And if you think he'll go out, and collect some more wobblies for you—" She stiffened in sudden horror. A piercing, long-drawn scream had reverberated across the glassite-walled sleeping turret, congealing her vocal chords, and turning Carstairs' blood to ice. It was followed by a silence so cloying that it seemed to muffle the tick of Carstairs' Greenwich-synchronized wrist watch.

With a startled oath, he snatched an oxygen mask from an overnight bag, clamped it on his face and rushed to the window. Throwing the casement wide, he strode out on the railed observation platform which half-encircled Gleason's towerlike dwelling.

BENEATH him stretched the foothills of the mightiest mountain range on Luna. Coruscating in the light of brittle stars, they arose precipitously from an ash-strewn plain, and though the smallest of them would have dwarfed a full-fledged mountain on Earth they seemed of pygmy dimensions when his gaze swept upward over the Gargantuan peaks beyond.

A strangled sound came from behind him. He swung about, his lips tightening. Vera was standing just outside the window.

"John," she choked. "That scream came from downstairs. You can't see anything from here. The wobblies wouldn't be visible in this glare."

The scream came again. It was audible now on the platform, a hideous, tormented wailing which seemed to drift up from below.

"It's coming from Gleason's sleeping turret," Carstairs said. "He sleeps with his oxygen mask on and his windows flung wide. I just wanted to make sure."

"Then why are we standing here?" Vera choked. "Oh, he's dying!"

"Get back inside," Carstairs rapped. "You ought to have more sense than to come out here without a mask."

"John, are the wobblies attacking him?"

"It couldn't be the wobblies. They're not carnivorous, and their nettles merely irritate the skin a little. Now get back, before your lungs buckle into folds."

Vera obeyed. She didn't stay in Carstairs' turret, but ran breathlessly through the door, and down a cold-lighted corridor to a spiraling flight of black plastic stairs. Down them she raced, oblivious to the torment in her lungs. Carstairs descended in slower strides, but the length of his legs kept him constantly at her side. With almost simultaneous movements he had thrown off the blankets, pushed the oxygen mask back over his forehead and wrapped a dressing gown around his rangy bulk.

"Take it easy, Vera," he cautioned. "If you drop dead, you'll be sorry later on." On dim walls on both sides of the stairway loomed imaginative paintings. Segrelles' Mountains of theMoon and Degrasse's Seas of Saturn. The tower was richly furnished, dark and awesome from its observatory roof to the deep cellars underground where Gleason's choicest wines were stored. In one aspect of his personality Gleason was an epicure, almost a sybarite. A scientific Gleason had welcomed the director of the Interplanetary Gardens to the Lunar Apennines, but Carstairs knew that there were other, more riotous Gleasons. There was a Gleason who devoutly admired chorus girls from the Twenty-first Century follies, a Gleason who went on periodic binges, and a Gleason who liked to gamble for high stakes over stacked chips at midnight.

Gleason's sleeping turret was at the end of a long, winding corridor on the third floor of the tower. Vera got to the door a split second ahead of Carstairs. Although it did not seem to be locked, the barrier creaked noisily and resisted her frantic tuggings.

"John, you'd better put your shoulders to it," she whispered hoarsely. "It seems to be stuck. Oh, John, I'm frightened."

Carstairs needed no urging. Bracing himself, he hurled his massive shoulders against the portal. There was a grinding crunch, and something clattered to the floor inside the turret. His face purpling, Carstairs pushed the door vigorously inward.

Vera pressed in after him, so closely that her breath fanned his neck. His shoulders half-blocked her view, but she could see chairs, a dresser and the upper portion of Gleason's bed. She could see Gleason sitting upright in his bed.

Her vision was superior to Carstairs', and wider in scope. She could see obscurely in the dark, and sharply in a dim light. The turret was bathed in a pale, sickly radiance. A cry rasping in her throat, she reeled forward and gripped Carstairs' shoulders with both hands.

CHAPTER II

Flight and Pursuit

IN THE center of the turret stood three huge wobblies. Their tendrils were weaving about in the gloom, and they had grouped themselves in a semicircle around the rigidly distorted figure of Gleason. Like plant ghosts they hovered above him, their body-roots glowing with a faint, spectral radiance. Unutterably terrifying they seemed, but what drove the blood in torrents from Vera's heart was Gleason's bulging eyes, and gruesomely sardonical grin.

"John, he's dead," she husked, her voice like a whisper from the tomb. A convulsive contraction twisted Carstairs' rough-hewn face. Swiftly he strode to the bed, ignoring the nettles which the tallest of the three wobblies instantly flung at him. One grazed his right cheek, another embedded itself in his shoulder.

He winced, and clawed at his flesh with his fingers, as though the downy "strawberry" had been dipped in acid, and was corroding his skin. Actually the gesture was instinctive, and on a par with nail-gnawing in a crisis.

Although Carstairs was no stranger to post-mortem appearances, his examination of the still figure was brief. Nothing can be done for a corpse, and Gleason had unmistakably stopped breathing. The risus sardonicus which distorted his features seemed to relax a little as Carstairs drew the sheets up over him. Shuddering, he turned from the bed. Vera was staring at the wobblies with terror stenciled on every lineament of her twitching face.

"John, did these ghastly things attack him?" she husked.

Carstairs shook his head. "How many times must I tell you that wobblies are not flesh-eaters," he said chokily. "They hurl nettles to protect themselves from their natural enemies, but otherwise they're harmless. When Gleason observed them on the mountains he took copious notes. They're freakish, but harmless perambulating plants."

The appearance and behavior of the wobblies seemed to belie Carstairs' words. They now hurled themselves across the dead man's bed, plucking with quivering tendrils at the sheets which covered him. Hideously manlike they seemed, with their gray and eroded-looking body-roots writhing against the sheets.

Tall they were, at least seven feet in height, and proportionately broad of shoulder. The fact that they had three tendrils on each side of their torsolike bodies in lieu of arms, and that they moved, when erect, on stumpy legs which caused them to wobble grotesquely did not detract from the illusion of humanness which their appearance conveyed.

Staggeringly weird they seemed when they used their nettles, for the flabby sacks in which the prickly

"strawberries" grew resembled the belly pouches of kangaroos, and the nettles had to be plucked out, and hurled. Jocularly, Gleason had called Carstairs' attention to the fact that a wobbly with its tendril arm extended, and its body twisted sharply in the act of hurling a nettle looked not unlike a pitcher in the old Earth game called baseball.

But now Gleason was no longer capable of jocularity, and Carstairs' expression was as grim as death. He was sniffing at the air and staring at his hands, as though bewildered by his ability to flex his fingers when his spine was a column of ice, his tongue a swollen mass of jelly.

"John, what is it?" Vera whispered hoarsely. "I don't smell anything."

"It would be better if you did," Carstairs husked. "Vera, this is devilish. Something utterly diabolic has occurred here. Yet there isn't a mark on him."

"What, John? What is it?"

"It—it defies reason. There are unmistakable evidences of foul play. Brownish mucous membranes, dilated pupils."

He returned to the bed and bent over the still figure lying there. His nostrils quivered, flared.

"The characteristic odor," he grunted. "But only his body exhales it."

"Uncle always was eccentric," said a cynical voice from the doorway. "In death as in life—peculiar, different."

Carstairs turned about on his heels, his jaw hardening.

The youth standing in the doorway had a sickly leer on his face. He was wearing black silk pajamas and he had thrown a monogrammed bath towel about his shoulders and knotted it foppishly in front.

CARSTAIRS had met Gleason's weak-chinned, dissolute nephew several times on Earth, and had hardly been able to stomach the youth's exaggerated mannerisms, and air of knowing he would someday inherit his uncle's wealth.

Henry Gleason Showalter was unmistakably intoxicated, but his sneering manner did not seem to emanate from the alcohol in his brain. His gaze was steady enough, and his voice had a quality of smirking contempt for the living and the dead which chilled Vera to the depth of her being. Before she could draw away from him he patted her arm. "You're right in your element, aren't you?" he sneered. "Helping him with his police work."

Carstairs saw red. He advanced upon the youth in three long strides, grabbed him by the shoulders and shook him until his jaw sagged.

"You cold-blooded little rotter," he grated. "Your uncle is dead. Doesn't that mean anything to you?"

"In his present condition, how could it mean anything?" asked a silky voice from the doorway. "He's been drinking steadily for hours."

Mona Clayton looked hard, cynical. She looked infinitely more cynical than Gleason's nephew, but she had more strength of character than the weak-chinned youth, and knew when and how to keep her thoughts to herself. The fact that she was that youth's fiancée had amazed Carstairs at first, but after conversing with her in Gleason's presence he had decided she was nobody's fool. She was marrying young Showalter for the money he'd eventually inherit. A gold-digger, if ever there was one. A hard, calculating little minx.

Behind her in shadows hovered Lee Chan, Gleason's Chinese butler, his once yellow face drained of all color.

"The master is dead," he wailed, wringing his hands. "He was the kindest man I ever knew. The very kindest man."

Vera crossed to Carstairs' side and tugged urgently at his arm. "John, control yourself!" she pleaded thickly. "Set him down."

"Would you rather I squeezed the rottenness out of him?" Carstairs grunted. "Just say the word." There was a sudden, deafening roar, and an energy pellet thudded into the wall behind Carstairs' head, shaking the entire turret. Mona Clayton screamed, and Carstairs leaped backward with a startled oath, carrying the youth with him.

Two more blasts came in staccato sequence. The window flamed orange, and a thin ribbon of smoke drifted into the turret from the darkness beyond.

Carstairs knew that a Gierson automatic pistol held five energy pellets. He also knew that Interplanetary Patrol regulations prohibited fancy weapons on the moon. The chances seemed to favor a Gierson, and a nearly exhausted clip.

Carstairs hurled Showalter from him with a snort of disgust. Three furious strides carried him to the window; a raised right foot and a leverage jounce from his left heel lifted him over the sill into the cold lunar night.

From the ventilator turbines at the base of the tower thin currents of scorching air ascended, to be instantly moderated by the cold of space. His shoulders etched in Earthlight, a cloaked figure was running along the observation platform toward what appeared to be a mistily weaving spiral of light. Pulling his oxygen mask down over his face, Carstairs pounded after him, his breath congealing on the frosty air. His energy carried him on with incredible speed. The moon's light gravity put wings on his heels, and lengthened his strides till his dressing gown swirled up about his shoulders, and streamed out behind him like a wind-lashed cloak.

His lips were contorted with savage mutterings when the spiral resolved itself into the stern light of a small vacuum plane. The machine was poised at the edge of the platform, its forward struts gleaming in the Earthlight, its magnetic traction vanes humming.

EVEN as Carstairs' gaze swept over it, the fleeing figure heaved itself into the pilot's seat and bent sharply forward. There was a sudden, vibrant roar, and the plane zigzagged along the edge of the platform, and took off so abruptly that Carstairs nearly lost his grip on the strut toward which he had literally dived.

Clinging with both hands, he let his long legs dangle, and cursed himself for a madman. The plane rose sharply and then swooped, descending toward the foothills below in a graceful, hawklike glide. Carstairs looked down, his spine congealing. Sheer height, when viewed from a solid structure, is seldom terrifying, but it is quite otherwise when the observer is clinging to the thrumming struts of a circling plane. Beneath him yawned a dizzying gulf of emptiness, walled with darkness and substructured with peaks which looked like stalactites in reverse, each one of which seemed capable of impaling him, and rotating him in squirming agony till the end of time.

"Maybe it wasn't such a good idea," he muttered between clenched teeth, tightening his grip on the strut. Down the plane swooped and down. It had ceased to descend gracefully, had begun to gyrate. Like a wounded bladder-bird, it swooped to right and left and quivered from beak to stern. Carstairs' nerves were shrieking when it settled to the ground in a deep gulch between two peaks and glided to a halt with a barely perceptible jolt. White-lipped, he dropped to the ground, and tore around the front of the plane to the pilot compartment.

It was a reckless thing to do, for the emerging pilot blasted from the hip the instant he discovered that he had a passenger. He stood half-out of the pilot seat, grasping the strut with one hand, and emptying his automatic in Carstairs' direction.

Two blasts echoed between hollow peaks as Carstairs clambered over a heated vane, and gripped the wrist of his assailant. "You're a bum pilot, Bowles," he panted. "You're also a bum marksman. It stands to reason, doesn't it, that you can't be good at this?"

He struck the other on the jaw as he spoke, rocking his head back. To his amazement the eyes opposite him did not glaze. Instead, fury flamed in them, and the jaw that he had jolted seemed to stiffen.

"That's what you think!" came in a hoarse bellow.

Limbs interlocked, the two men dropped to the ground and rolled over. The fact that Carstairs' had recognized his assailant as George Bowles, Gleason's huge and taciturn gardener, was no help to him. The man was six feet six, and as strong as an ox.

He twisted Carstairs' arm back, and bit him in the shoulder.

"Fight clean, Bowles," Carstairs gibed, concealing his agony with a grin which increased the other's rancor. Furiously he pummeled Carstairs, ignoring the angular knee which the still grinning botanist rammed into his stomach and the shower of fisticuffs which spattered against his close-cropped head, rocking it to and fro.

Bitterly Carstairs realized that he had underestimated his adversary. The man could take it, and he could ladle it out. He could absorb so much punishment that Carstairs' plight was not an enviable one. He was flat on his back, and Bowles was trying viciously to break his arm, and almost succeeding. Worse, the big gorilla's punches were packed with dynamite, and coming faster and faster. Carstairs fought with all his strength, but gradually he felt himself growing weaker. In desperation he squirmed and twisted, dragging himself over the ground, his shoulders jerking. He reached a jagged outcropping of rock on the slightly sloping floor of the ravine, where he furiously endeavored to raise his shoulders when Bowles began violently to shiver. The half-Nelson which he had thrown about Carstairs relaxed, and a convulsive shudder shook him.

Stunned, Carstairs wrenched his arm free, twisted about and raised his fist for a crushing blow that wasn't needed. Bowles had rolled over on his side, and was lying utterly rigid, a bubbling froth on his lips. Clinging to his neck was a small, strawberry-colored nettle.

Horror struck, Carstairs stared at it, unable to believe his eyes. It was in all respects an exact duplicate of the one which was still clinging to his own shoulder, except for one thing. It was scarcely one-fourth as large.

CHAPTER III

Blood Pressure of a Plant

A SHRILL ululation caused Carstairs to raise his eyes and glance startlingly about him. The wobbly he saw was one-fourth the normal size. A baby wobbly, an unmistakable fledgling of the species which Gleason had captured and studied was standing a few feet away, its tendrils fluttering in the hot air currents from the tower's turbines which were swirling down into the gulch in erratic gusts, its small root-body quivering in infantile panic.

Lifting Bowles' limp body in his arms, and carrying it to the vacuum plane was a nerve-racking ordeal, because Car-stairs was sure he had another corpse on his hands. It wasn't until he was back in the tower, with a stirring and groaning Bowles clutching at his sleeve, that the truth struck him like a bolt from the blue, rocking him back on his heels and shedding dazzlement in all directions. The big, pugnacious bruiser was allergic to nettles! So allergic that the shock of one entering his flesh had brought on a convulsion and laid him out limp. It wasn't such a rare mishap from a medical point of view, but it left Carstairs stunned and gasping. That big, husky giant—brought low by a nettle flung by a baby wobbly!

Carstairs deposited Bowles on the floor of Gleason's sleeping turret, directly under a dim cold light bulb. The big, rectangular chamber had quieted down, for Vera Dorn had not been idle in Carstairs' absence. She had sprayed a narcotizing vapor over the three wobblies, and locked them up in a metal herbarium. She had sent Mona Clayton back to her sleeping turret on the floor below, and turned on Showalter a glance so withering that he had slunk furtively into shadows. The nephew was standing now in a dim recess behind Gleason's bed, his eyes boring holes in the gloom.

Bowles raised himself on his elbow, trying desperately to talk his way back into Carstairs' good graces. His voice was husky, and all the pugnacity had gone out of him.

"I lost my head when you swung at me," he muttered. "I've nothing against you, Carstairs, but when you came at me like that I had to defend myself, didn't I? I'm hot-tempered, sure. But I didn't kill Gleason. It was that little hyena there."

Mentally Carstairs docketed for reference the astonishing fact that everyone referred to Gleason's nephew as a hyena, skunk, or snake. He gnawed at his underlip, and fixed Bowles with an accusing stare.

"You blasted before I clipped you," he said. "You tried to shoot me down in cold blood. You tried to shoot Showalter down. Why did you crouch in darkness outside that window and try to drill him?"

"I'll tell you why," Bowles choked. "I took my job here seriously. I like flowers. That may seem sort of screwy to you, but I mean it."

"It doesn't," Carstairs assured him.

"Well, you've seen Gleason's orchids. Glass-encased, sure, with air pumped in. Tropical terrestrial plants—nothing fancy about 'em. But I took a personal pride in them."

"You did a good job," Carstairs admitted. "Raising perfect plants under artificial sunlight is a tough assignment."

"That's it —perfect," Bowles cried eagerly. "My orchids were perfect. Perfect, you hear? I liked my job, and I wanted to keep it. But he didn't want me too."

He gestured toward the shadows where Gleason's nephew stood. Showalter had lit a cigarette and was puffing on it furiously.

"He came stumbling into the greenhouse last night as high as a kite," Bowles muttered accusingly. "He tore my flowers up by the roots. He upset trays, and turned a hose on my finest bed. Did you ever see fine blooms flattened into a mud soup?"

Carstairs nodded sympathetically. "I would have perhaps killed him myself. We're all savages when something rasps us in a vital spot. But you had a few hours to calm down in."

"Yeah, but he ran to his uncle like a dirty little schoolboy sneak. He accused me of tanking up, and throwing my own trays around. Gleason gave me my notice before he turned in at midnight. He called me a liar, refused to hear me out."

"He wouldn't listen to any honest man or woman," shrilled a quavering voice from the doorway. "He deserved to die. He was a hard man—cold and unjust. There was no compassion in him. I'm glad he's dead!"

CARSTAIRS swung about. A frail, white-haired old woman had slipped into the room and was standing by Vera's side. As Carstairs stared at her in consternation she raised a clawlike, veined hand and pointed at the still figure on the bed.

"May you rest in torment, James Gleason," she shrilled.

Carstairs had had about enough. He crossed to the door in three long strides, turned the old woman about, and guided her gently but firmly into the corridor.

"Go back to your room," he said. "And stay there. If I need you, I'll send for you. You've been a good housekeeper to James Gleason. Why should you hate him so much?"

The old woman shook her head. "It's not for me to be telling you," she muttered. "You'll find out soon enough."

Returning to the sleeping turret, Carstairs swabbed sweat from his forehead and spoke crisply to Vera Dorn.

"I said that something diabolic had occurred here. I'm afraid it's worse than that. Listen carefully, Vera. I'm going to take one of the wobblies up to my turret. I want you to bring me Gleason's notes. All of them, you understand? His day-by-day observations, the complete record of what he saw on the mountains when he studied the wobblies from behind a blind. His speculations as to their feeding habits, the chemical and osmotic tests which he made on the three specimens which are now our guests."

"But you've almost memorized those notes," Vera protested.

"I know, but there are minor details I may have overlooked. One thing more —give me fifteen or twenty minutes' leeway before you snap to it."

Twelve minutes later Vera Dorn tapped apprehensively on the door of Carstairs' sleeping turret.

"Come in," a grim voice said.

Vera obeyed, shivering. She knew John Carstairs. He was never so unpredictable as when he asked her to do something for him when he had all the pieces in an unspeakably terrifying case. She knew that he was at the crucial stage. The glint in his eyes, his air of repressed excitement, and his willingness to permit four vengeful people to remain at liberty indicated that he was prepared to act swiftly and inexorably. Vera Dorn had steeled herself to encounter an unusual manifestation of Carstairs' genius at work, but the sight which she saw when she shut the door firmly and turned to face her employer was so completely ludicrous that it chilled her more than a gruesome exhibit would have done. In a way, it was a little gruesome—comically so, perhaps, like a child's rag doll dangling from a hangman's noose —but unspeakably nightmarish in its implications.

One of the wobblies was sitting upright in a chair by the window, its tendril-arms bound by thin wires and its stumpy legs interlocked. The anesthetic vapor which Vera had sprayed over it had worn off, and it was squirming about and emitting shrill ululations.

Clamped to its rugose, tapering head was a semi-circular metal disk, somewhat resembling an aluminum eye-shield. From the disk a thin glass tube descended to the creature's "waist" and branched off at right angles to its body-root. A few inches beyond the bent section of the tube the glass terminated in a flexible rubber extension which carried the tubular portion of the apparatus across the floor to Carstairs' hand. Carstairs was sitting on the edge of his bed, pressing a large rubber bulb at five-second intervals. Every time he gave the bulb a squeeze a pale, greenish fluid bubbled and frothed in the glass portion of the tube, occasionally ascending to the half-disk on the plant creature's head.

"Good Lord!" Vera Dorn choked.

"Quiet, Vera," Carstairs cautioned. "If the pressure goes any higher we'll have a dead wobbly on our hands."

"John, are you out of your mind? Why did you truss that poor thing— pressure! John, what do you mean?"

"I'm taking its blood pressure," Car-stairs said. "To be strictly accurate, its sap pressure, although the fluid which circulates in its veins contains actual blood-plates, and mononuclear cells containing basophilic granules. Its blood pressure is unbelievably high now. So high that—" He stared at her steadily. "Well, it will be labeled Exhibit A, Vera. And I wouldn't want to be in the shoes of a certain party when I lay my findings before a jury."

VERA DORN'S jaw sagged. "John Carstairs, how can you take the blood pressure of a plant? I never heard of such a thing."

"Vera, I thought you majored in botany at college," Carstairs said acidly. "Perhaps you'd better go back for another semester of intensive osmotic research. You know, summer course for girls with low I.Q.s who can't quite make the grade."

Vera flushed scarlet. "What has osmosis to do with taking the blood pressure of a plant?"

"Plenty," Carstairs grunted. "Most plants, as you know suck nourishment from the soil through their roots by osmosis, and draw it up through the woody part of their stems by capillary attraction and a process known as transpiration. All these processes are accelerated by the pressure of sugar and salt in the sap."

"But—"

"Let me finish, Vera. In terrestrial plants the nutrient fluid is an amalgam of common minerals. But in lunar plants a different kind of nourishment is sucked up, and their veins are filled with specialized chemicals capable of accelerating its absorption.

"When osmosis is accelerated to an abnormal extent a plant's blood pressure begins to rise. It may reach twenty or thirty atmospheres. On Earth many plants exhibit the symptoms of high blood pressure, but leaf or tendril evaporation drains off the excess nourishment and keeps them from going into convulsions.

"Here on the moon there is no such safety valve. Plants scarcely perspire at all, due to environmental factors. They have to eat sparingly, or else."

"But no plant or animal ever eats sparingly," Vera protested. "A dog, for instance, never knows when to stop, and the same rule applies all down the biological scale."

Carstairs nodded. "True. But you're forgetting that living creatures gorge themselves only when there is an abundance of nourishment. Wobblies feast on a substance which is rare on Luna. Being perambulating plants, they have to suck it in from the nearly airless vacuum which is the moon's atmosphere through their body roots, and it costs them a tremendous effort. Ordinarily their blood pressure remains low because they have adapted themselves to an environment in which nourishment is scarce.

"But nourishment wasn't scarce here in the tower last night. I've a very sick wobbly on my hands, a wobbly that is going to put a noose around somebody's neck. That wasn't Gleason we heard screaming last night. It was three wobblies with high blood pressure, ululating together in his sleeping turret." Vera's lips were white. "Whose neck, John?"

Carstairs shook his head. "No, you don't. Vera. You'll know when I'm sure. I've got to get answers to a couple of space-o-grams first. If what I suspect is true, the murderer is no ordinary criminal. He—or she—must possess a mind of the first order of malign cunning."

He shuddered. "It gives me a sick feeling in the pit of my stomach."

"It does me, too," Vera flared, biting her lip. "Although you won't tell me a darned thing about it. I'm that way—sympathetic when my boss gets a tummyache."

Carstairs scowled. "All right, Vera, I asked for it. You're hard and unsympathetic, but you understand me. I feel sort of helpless when I close in for the kill. I like to be—well, coddled." Vera kissed him, patting his cheek. "Sure, I know. That's why I'm supposed to be in love with you."

"Aren't you?"

"I think maybe I am." She looked at him hopefully.

Carstairs' eyes narrowed. "All right, then you can do something for me. I want you to get them all together in Gleason's turret — Bowles, Showalter, the Chinese butler, Mona Clayton, and that sweet, white-haired grandmother, Miss Newton. Get them together, and give me twenty more minutes. When I come down I'll try to satisfy your curiosity."

"John Carstairs, if you got romantic for once in your life and whispered sweet nothings to me without an ulterior motive," Vera declared, "do you know what I'd do?"

"No, what?"

"Turn into a wobbly. I'd have to do that to keep my blood pressure down." She went out, slamming the door so violently that the wobbly emitted a long-drawn ululation, and squirmed violently in its chair.

CHAPTER IV

Botanical Stoolpigeon

WHEN John Carstairs appeared in the doorway of Gleason's sleeping turret the five white-lipped people gathered there stared at him as though he were a visitor from Saturn. His expression was utterly inscrutable, and an almost godlike detachment seemed to emanate from him. He hoped that none of the five suspected that he felt like a scared kid with one exploratory thumb poised above a high-voltage electric wire.

Nodding at Vera, he crossed in silence to the bed where Gleason's sheet-covered body lay, made sure that the cold light did not fall directly on his head and shoulders, and swept the five suspects with his gaze.

He began to talk at once, fixing Henry Showalter with an accusing stare. The nephew began instantly to tremble. His air of vicious cynicism had dropped from him, like a cloak that he had found much too costly to wear.

"If there is any crime you would not have committed to get your hands on your uncle's wealth, Showalter," Carstairs said, "it would have to be mentioned in whispers by anyone with an ounce of decency in him. You were quite capable of killing your uncle, and you would have experienced no remorse. I've a pretty complete account here of your—well, I'll be charitable, and call them escapades—on Earth.

"I sent a space-o-gram to the New York Police Department, Mr. Showalter. You've a record of seven arrests, ranging from drunkenness to arson. You're a thorough rotter, but—" He frowned. "You did not kill him. You are neither a chemist or a genius." Carstairs turned his gaze to Gleason's housekeeper with a shudder of disgust. The white-haired old woman quivered. "Why are you staring at me like that? Do you think I killed him?"

"No," Carstairs said. "But you are suffering from the same disease, I'll be charitable and call it ungratefulness. Gleason raised your salary every time you came to him with a hard luck story. The last time you rasped his patience a little, and he didn't give you as much as you thought you deserved. Consequently, you hated him."

He shrugged, turning to the Chinese butler. "You're a pretty good guy," he said. "You didn't kill him, did you, Lee Chan?"

The yellow man shook his head. "He was a pretty good guy himself," he singsonged. "The kindest man I've ever known."

"Yes, there are still a few kindly people left in the world," Carstairs agreed, swinging suddenly toward George Bowles and Mona Clayton. They were standing close together, their faces drained of all color, their eyes fastened on Carstairs.

"Sulphuretted hydrogen, Bowles," Carstairs said softly, "causes symptoms which end rapidly in death. It is one of the deadliest gases known, comparable only to cyanide fumes in the swiftness with which it acts. If the concentration is marked, fatal effects by inhalation are immediate." His jaw muscles tightened. "Oh, you were clever, Bowles. Posing as a humble lover of flowers, an eccentric with only one consuming passion in life. A simple gardener, living for his plants."

"You're crazy, Carstairs," Bowles choked. "What are you driving at?"

"You were not only interested in orchids, Bowles," Carstairs continued relentlessly. "You were interested in wobblies, and you persuaded Gleason to let you see his notes. Your thumbprints are on the sheets Miss Dorn brought to me. You are also a toxicologist, Bowles. You worked in a chemical laboratory on Earth, and you knew that sulphuretted hydrogen has one disadvantage as a killing agent.

"It leaves an odor, the strongest odor of any lethal chemical, one which hovers in the air and impregnates the flesh of the victim."

Mona Clayton's agitated voice rang out across the chamber. "He lies! Oh, darling, defend yourself, tell him—"

"Darling, is it?" Carstairs rasped. "I thought so. Bowles, you knew that sulphuretted hydrogen leaves an unmistakable odor, but you also knew that the wobblies feast on it. It is their natural source of nourishment. It clings to the walls of deep gulches in the mountains, and they suck it in by osmosis through their permeable body-roots!"

MONA CLAYTON uttered a faint moan. But the botanical detective went on relentlessly.

"Last night you treated the three wobblies which Gleason had captured to a feast. You smashed the glass herbarium and released them, after pumping sulphuretted hydrogen into Gleason's sleeping turret through a sprayer from outside the window to kill him. You knew that wobblies can scent sulphuretted hydrogen half across the moon, and you figured they would streak like starved bloodhounds to Gleason's turret.

"They did. Vera Dorn encountered one in the corridor and one in her sleeping turret, but wobblies are like that. They know that a roundabout way is often the quickest distance between two points on the Moon. They climbed down outside, and entered through the window which you had purposely left open. When their blood pressure rose and they ululated, Miss Dorn and I raced downstairs, to discover they had sucked up all the sulphuretted hydrogen in the air leaving it crisp and odorless.

"Gleason usually slept with his windows thrown wide, but last night you must have had to raise the pane to pump the gas in. Although we found the casement the way you had left it, there was still air in the room. The wobblies would have sucked that giveaway odor out of Gleason himself, but we got to him in time, and a little of it lingered when I bent over him. You thought the wobblies would clear away every trace of the gas, and make it look as though Gleason had died of natural causes." Carstair's eyes were steely slits. "When you saw I had it tabbed as murder you tried to throw suspicion on Showalter by accusing him of upsetting your trays last night, and subtly hinting that maybe Gleason hadn't quite believed his nephew's version of the affair either. In other words, you implied that Showalter was in danger of being cut off without a cent."

"That's a lie," Bowles muttered hoarsely. "You're trying to frame me, Carstairs."

"Think so? I've got a space-o-gram here from Earth which says that you and Miss Clayton have been partners in crime for a decade, and are wanted for blackmail and homicide by the San Francisco police.

"It was beautifully planned, Bowles. All you had to do was murder Gleason and the rest would unwind like a carefully oiled spring. Showalter would inherit a fortune, Mona would marry Showalter, and then you and Mona would take a vacation together, with Showalter's inheritance in an overnight bag to brighten the trip."

Carstairs looked straight at Mona Clayton. Her hands were clenched and her features seemed all wrenched apart. "You should have picked a less allergic partner, Mona. I suspected him from the first, but what really clinched it was his aversion to nettles. He plucked most of the nettles out of the wobblies with tweezers before releasing them.

"It was just blue funk, I guess—he couldn't bear the thought of being in the same tower with nettle-hurling wobblies running around loose."

"But one of those wobblies hurled a nettle at me, John," Vera said. "And at you. You've one in your shoulder now."

Carstairs nodded and held up his hand. "I said most of the nettles, Vera. When I examined the wobblies a half-hour ago I couldn't find a nettle in them. I knew then that I had him, and I could see the noose tightening about his neck. The fact that he must have overlooked three nettles deep in the pouch of the tallest wobbly won't influence the jury much. Three nettles! One for you, one for me, and this one for evidence of—"

Before he could finish Bowles dived for the window. There was a splintering crash as his gigantic bulk tore a hole in the pane and vanished.

Carstairs crossed the room in a flying leap. For the barest fraction of a second he paused to hurl the casement open and clamp on his oxygen mask. Mona Clayton screamed, and Vera grasped her arms from behind and held on tight.

Cursing himself for a sissy, Carstairs tore out into the lunar night. His reluctance to tear his face to ribbons had proved a costly mistake. Bowles was thirty feet away, and running along the edge of the platform toward a weaving spiral of light.

Instantly Carstairs had a vision of himself descending once again into the foothills on the thrumming strut of a vacuum plane. It was an appalling vision and it chilled his heart like ice. It also stopped him in his tracks.

He hurled the nettle with surprising ease, his body twisting a little like a pitcher in a game called baseball. Bowles shrieked. Spinning about on his toes, he tottered for an instant at the edge of the platform and then plunged downward, his body revolving as he fell toward peaks which looked like stalactites in reverse, each one of which seemed capable of impaling him and rotating him in screaming agony to the end of time.

Carstairs turned away, shaken, and a little sick.

DARLING," Vera said, eternities later, "you'll have to operate on both of us. There is still one nettle in my shoulder and one in yours. You can't just pluck them out."

"No, I suppose not," Carstairs grunted, reaching for a bottle of antiseptic and a cotton pad. "But next time you bump into a wobbly in the dark, try talking to it. It will quiet right down."

"You mean my voice would calm it down?" exclaimed Vera Dorn, her eyes glowing. "John, how sweet of you."

Carstairs smiled, dabbing at her shoulder. "When you pay a woman a compliment, she always stays put for a minute. I've never known it to fail."

"Then you didn't mean that—about my voice?"

"Oh, certainly, but I wanted to get you to hold still."

The silence in the big, rectangular turret was broken by the sound of a slap.