HE FIRST ONE HE got was worthless.

The base was so poorly leveled that any vibration at all disturbed it. The action of its moving parts was loose to the point of wobbling. The mirror kept moving out of position because its pivots weren't tight enough. Moreover, the instrument had no substage to hold condenser or polar?izer. It had only one nosepiece, so that he had to remove the object lens when he wanted any variation in magnification. The lenses were impossible.

But, of course, he knew nothing about microscopes, and he'd taken the first one he'd found. Three days later he hurled it against the wall with a strangled curse and stamped it into pieces with his heels.

Then, when he'd calmed down, he went to the library and got a book on microscopes.

The next time he went out, he didn't come back until he'd found a decent instrument; triple nose stage, substage for condenser and polarizer, good base, smooth movement, iris diaphragm, good lenses. It's just one more example, he told himself, of the stupidity of starting off half-cocked. Yeah, yeah, yeah, he answered disgustedly.

He forced himself to spend a good amount of time familiarizing himself with the instrument. He fiddled with the mirror until he could direct a beam of light on the object in a matter of seconds. He acquainted himself with the lenses, varying from a three-inch power to a one-twelfth-inch power. In the case of the latter, he learned to place a drop of cedar-wood oil on the slide, then rack down until the lens touched the oil. He broke thirteen slides doing it.

Within three days of steady attention, he could manipulate the milled adjustment heads rapidly, could control the iris diaphragm and condenser to get exactly the right amount of light on the slide, and was soon getting a sharply defined clarity with the ready-made slides he'd got. He never knew a flea looked so godawful.

Next came mounting, a process much more difficult, he soon discovered. No matter how he tried, he couldn't seem to keep dust particles out of the mount. When he looked at them in the microscope, it looked as if he were examining boulders.

It was especially difficult because of the dust storms, which still occurred on an average of once every four days. He was ultimately obliged to build a shelter over the bench.

He also learned to be systematic while experimenting with the mounts. He found that continually searching for things allowed that much more time for dust to accumulate on his slides. Grudgingly, almost amused, he soon had a place for everything. Glass slips, cover glasses, pipettes, cells, forceps, Petri dishes, needles, chemicals--all were placed in systematic locations.

He found, to his surprise, that he actually gleaned pleasure from practicing orderliness. I guess I got old Fritz's blood in me, after all, he thought once in amusement.

Then he got a specimen of blood from a woman.

It took him days to get a few drops properly mounted in a cell, the cell properly centered on the slide. For a while he thought he'd never get it right.

But then the morning came when, casually, as if it were only of minor import, he put his thirty-seventh slide of blood under the lens, turned on the spotlight, adjusted the draw tube and mirror, racked down and adjusted the diaphragm and condenser. Every second that passed seemed to increase the heaviness of his heartbeat, for somehow he knew this was the time.

The moment arrived; his breath caught. It wasn't a virus, then. You couldn't see a virus. And there, fluttering delicately on the slide, was a germ. I dub thee vampiris. The words crept across his mind as he stood looking down into the eyepiece.

By checking in one of the bacteriology texts, he'd found that the cylindrical bacterium he saw was a bacillus, a tiny rod of protoplasm that moved itself through the blood by means of tiny threads that projected from the cell envelope. These hairlike flagella lashed vigorously at the fluid medium and propelled the bacillus.

For a long time he stood looking into the microscope, unable to think or continue with the investigation. All he could think was that here, on the slide, was the cause of the vampire. All the centuries of fearful superstition had been felled in the moment he had seen the germ.

The scientists had been right, then; there were bacteria involved. It had taken him, Robert Neville, thirty-six, survivor, to complete the inquest and announce the murderer--the germ within the vampire.

Suddenly a massive weight of despair fell over him. To have the answer now when it was too late was a crushing blow. He tried desperately to fight the depression, but it held on. He didn't know where to start, he felt utterly helpless before the problem. How could he ever hope to cure those still living? He didn't know anything about bacteria.

Well, I will know! he raged inside. And he forced himself to study.

Certain kinds of bacilli, when conditions became unfavorable for life, were capable of creating, from themselves, bodies called spores. What they did was condense their cell contents into an oval body with a thick wall. This body, when completed, detached itself from the bacillus and became a free spore, highly resistant to physical and chemical change. Later, when conditions were more favorable for survival, the spore germinated again, bringing into existence all the qualities of the original bacillus.

Robert Neville stood before the sink, eyes closed, hands clasped tightly at the edge. Something there, he told himself forcefully, something there. But what?

Suppose, he predicated, the vampire got no blood. Conditions then for the vampiris bacillus would be unfavorable.

Protecting itself, the germ sporulates; the vampire sinks into a coma. Finally, when conditions become favorable again, the vampire walks again, its body still the same.

But how would the germ know if blood were available? He slammed a fist on the sink in anger. He read again. There was still something there. He felt it.

Bacteria, when not properly fed, metabolized abnormally and produced bacteriophages (inanimate, self-reproducing proteins). These bacteriophages destroyed the bacteria.

When no blood came in, the bacilli would metabolize abnormally, absorb water, and swell up, ultimately to explode and destroy all cells.

Sporulation again; it had to fit in.

All right, suppose the vampire didn't go into a coma. Suppose its body decomposed without blood. The germ still might sporulate and--Yes! The dust storms!

The freed spores would be blown about by the storms. They could lodge in minute skin abrasions caused by the scaling dust. Once in the skin, the spore could germinate and multiply by fission. As this multiplication progressed, the surrounding tissues would be destroyed, the channels plugged with bacilli. Destruction of tissue cells and bacilli would liberate poisonous, decomposed bodies into surrounding healthy tissues. Eventually the poisons would reach the blood stream.

Process complete.

And all without blood-eyed vampires hovering over heroines' beds. All without bats fluttering against estate windows, all without the supernatural.

The vampire was real. It was only that his true story had never been told.

Considering that, Neville recounted the historical plagues.

He thought about the fall of Athens. That had been very much like the plague of 1975. Before anything could be done, the city had fallen. Historians wrote of bubonic plague. Robert Neville was inclined to believe that the vampire had caused it.

No, not the vampire. For now, it appeared, that prowling, vulpine ghost was as much a tool of the germ as the living innocents who were originally afflicted. It was the germ that was the villain. The germ that hid behind obscuring veils of legend and superstition, spreading its scourge while people cringed before their own fears.

And what of the Black Plague, that horrible blight that swept across Europe, leaving in its wake a toll of three fourths of the population?

Vampires

By ten that night, his head ached and his eyes felt like hot blobs of gelatin. He discovered that he was ravenous. He got a steak from the freezer, and while it was broiling he took a fast shower.

He jumped a little when a rock hit the side of the house. Then he grinned wryly. He'd been so absorbed all day that he'd forgotten about the pack of them that prowled around his house.

While he was drying himself, he suddenly realized that he didn't know what portion of the vampires who came nightly were physically alive and what portion were activated entirely by the germ. Odd, he thought, that he didn't know. There had to be both kinds, because some of them he shot without success, while others had been destroyed. He assumed that the dead ones could somehow withstand bullets.

Which brought up another point. Why did the living ones come to his house? Why just those few and not everyone in that area?

He had a glass of wine with his steak and was amazed how flavorsome everything was. Food usually tasted like wood to him. I must have worked up an appetite today, he thought.

Furthermore, he hadn't had a single drink. Even more fantastic, he hadn't wanted one. He shook his head. It was painfully obvious that liquor was an emotional solace to him.

The steak he finished to the bone, and he even chewed on that. Then he took the rest of the wine into the living room, turned on the record player, and sat down in his chair with a tired grunt.

He sat listening to Ravel's Daphnis and Chloe Suites One and Two, all the lights off except the spotlight on the woods. He managed to forget all about vampires for a while.

Later, though, he couldn't resist taking another look in the microscope.

You bastard, he thought, almost affectionately, watching the minuscule protoplasm fluttering on the slide. You dirty little bastard.