Again, no place has been set apart by nature for waste products but they flow wherever they can find an easy passage in the body, but a place has been set apart for all the natural residues; thus the lower intestine serves for the excretion of the solid nutriment, the bladder for that of the liquid; for the useful part of the nutriment we have the upper intestine, for the spermatic secretions the uterus and pudenda and breasts, for it is collected and flows together into them.