#preserving_substance__medium  (biology) a substance in which specimens are preserved or displayed
  supertype:  substance__matter  that which has mass and occupies space; "an atom is the smallest indivisible unit of matter"
  subtype:  contrast_medium__contrast_material  a substance that is opaque to x-rays; when administered it allows a radiologist to examine the organ or tissue it fills

No statement uses or specializes preserving_substance; click here to add one.