- feces
- nitrogenous waste
- mineral waste
- undigested matter
- dead cells
- shed structures
Operational definition
Accounting output.
Two distinct outward material flows:
- excretion — removal of compounds that entered internal physiological processing or were produced metabolically;
- egestion — expulsion of material that was ingested but not assimilated across the absorptive boundary.
The distinction is necessary for correct assimilation accounting.