The latter are usually organic or inorganic substances that are products of metabolism , and include crystals , oil drops , gums , tannins , resins and other compounds that can aid the organism in defense , maintenance of cellular structure , or just substance storage .
These are usually organic or inorganic substances that are products of metabolism , and include crystals , oil drops , gums , tannins , resins and other compounds that can help the organism in defense , maintenance of cellular structure , or just substance storage .