Viruses
Microscopic particles, molecules of nucleic acids (DNA or RNA), contained in a protein shell and capable of infecting living organisms. Outside the cell, V. behave like non-living chemical substances; multiplying when enter the host’s cells.
V. do not split in half like cells but accumulate many copies of themselves within a cell, using the host’s resources. By one hypothesis, V. are a transitional form between the alive and not alive.
Location: random books in reading rooms.