Bedlam Planet by John Brunner

qualification. But the portable device wasn’t sensitive enough to tell him what that was.
    Somewhat cheered, because the clean diagnosis implied that whatever else might have happened during his fit of insanity the principle that Earthly creatures didn’t pick up Asgard diseases still held good, he piled the kit, suit, and gun on the passenger seat of the boat and scrambled into the pilot seat himself. Gingerly, because if that animal had wrecked the radio one of its cousins might have ruined another and more essential piece of equipment, he checked the drive. The engine emitted a normal throbbing drone, and all the instruments read as they should.
    He was on the point of feeding power to the drive and heading for base, when he halted his hand an inch from the main control lever.
    Food?
    He twisted around in the seat and stared over his shoulder at the rack of cartoned meals within arm’s reach. They looked as he remembered, and as they should have looked, after he had drawn thirteen days’ allowance. One carton had suffered the attentions of alocal animal, and its corner was torn, but the thief had clearly found the contents inedible and left them alone after a few bites.
    I
ought to be hungry.
    He switched off the power and sat shivering as a vivid, revolting memory came clear in his mind. He had vomited, and spewed a great gout of liquid all over himself. What had been in him, that his stomach rejected so violently? And more alarming still: what was in him now, that he did not feel hungry despite not touching his packaged stores for ten mortal days …?
    He closed his eyes for a moment, for the world was tilting dizzily. He clutched the reassuring hardness of the control lever until his thinking calmed and he was able to face the important point that if he had managed to live by eating Asgard foodstuffs he must try and work out what they were. So far as he knew, Tai Men had not even begun a programme to determine whether native plants were nutritious. Possibly he had even chanced—blindly, crazily—across a key to the scurvy problem which had still been plaguing the colony the last time he spoke on the radio.
    He wanted desperately to head for the base island to see another human face, hear a voice and lie under a roof again. But he steeled himself against the impulse to leave right away. He gathered a camera and a biological sampling kit, and got out of the boat.
    For the best part of three hours he trudged back and forth around the island, trying to reconstruct his movements. He took a sample of water from the stream in which he had found himself when he recovered. Clearly, he had drunk from it without purifying it, and was none the worse. That was significant. So, too, were the gnaw-marks he spotted on the cabbagy stem of one of the shrubs, that at first he mistook for a blaze he had cut to show the trail. But those were the traces of teeth, not a machete.
    He collected samples of his own excrement, which he had dropped like an animal wherever the need overtook him, and sealed them in airtight bags. They were unattacked by the native scavengers—one of the reasons why sewage disposal was likely to become a major problem on Asgard, requiring all-chemical treatment without aid from bacteria—and he saw in them shreds of tough bark-like material, small round objects resembling tomato-pips, and other substances that had apparently gone through his bowel unaltered. Yet he had incontestably been nourished by his improbable diet. He was fit and strong, as though he had been under the supervision of an expert dietitian.
    Shaking his head, he returned to the boat with his load of samples. Having stowed them, he turned on the power for the second time, eased his craft up on its hoverducts, and set the automatics to take him back to the base at maximum speed, regardless of wasted power.
    During the terrible day and a half of suspense which he had to endure while the boat carried him along, he struggled to make sense out of