Page "Hypothetical types of biochemistry" Paragraph 9

Perhaps the most extreme example in science fiction is James White's Sector General: a series of novels and short stories about multienvironment hospital for the strangest life-forms imaginable, some of them breathing methane, chlorine, water and sometimes also oxygen.

Some of the species metabolise directly hard radiation and their environment doesn't differ much from the atmosphere of a star, while others live in near absolute zero temperatures.

All life forms are classified according to their metabolism, internal and external features, and more extreme abilities ( telepathy, empathy, hive mind, etc.

) with four letter codes.