Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         "crystal-kingdom"
           chemical substances
             chemical compounds
               Class hydrocarbons [CxHy] - compounds consisting of carbon and hydrogen only
                 Class alkanes [CnH2n+2] - saturated acyclic hydrocarbons
                   unbranched alkanes
                     [eicosane - C₂₀H₄₂] see icosane