Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         "crystal-kingdom"
           chemical substances
             chemical compounds
               Class nucleotides [HOP(=O)(OH)OCH2CH(O~)CH(OH)CH(Y)CH(base)~ (Y=H or OH)]
                 Class ribonucleotides [HOP(=O)(OH)OCH2CH(O~)CH(OH)CH(OH)CH(base)~]
                   adenosine diphosphate
                   adenosine monophosphate
                   adenosine triphosphate