Reviewed date: 2018 Jun 2
Contamination Crew is a short story in Nourse's Hospital Earth series. Red Doctor Samuel Jenkins and Green Doctor Wallace Stone have just finished a brief visit to the fourth planet of Mauki, where they encountered an unusual problem.
The entire population of that planet was found to be suffering from a mass psychotic delusion of rather spectacular proportions: namely, that they and their entire planet were in imminent danger of being devoured, in toto, by an indestructible non-humanoid creature which they called a hlorg.
Oh those poor primitive superstitious natives! Jenkins and Stone refer the Mauki IV problem to the Grey Service of psychiatry. Then they meet up with the General Survey Ship Mercy to return to Earth.
The Maukivi had described the hlorg in excruciating detail. He and Green Doctor Stone had listened, and smiled sadly at each other, day after day, marvelling at the fanciful delusion. Hlorgs, indeed! And such creatures to dream up—eating, growing, devouring plant, animal and mineral without discrimination—
The hlorg is real and it has gotten on board Mercy. The hlorg is a pink amorphous living blob that consumes everything it comes into contact with. It's going to eat the whole ship. The crew try everything to kill it. Nothing works--not slicing, not freezing, not boiling, not heat or cold, not antibiotics or dessicants or acids or blunt force trauma.
Except hydrochloric acid. That interferes with the hlorg's enzyme system and renders it vulnerable.
Mercy doesn't have enough hydrochloric acid on board to entirely kill the hlorg, so they use the only natural source of hydrochloric acid available: the human stomach. They cut off bits of the hlorg and eat it.