THERE is no need to argue whether "presbycolon" is a valid physiologic concept. As a term simply to imply the wretched bowel malfunction of so many elderly persons it has some usefulness. In this sense, presbycolon means primarily constipation plus its complications, mainly colon gas and impaction. It is common enough to rank with joint pain, dizziness, forgetfulness, depression, and bladder problems as one of the most frequent forms of misery encountered in the nursing home. Forms of Constipation Presbycolon in this sense does not imply a specific form of physiologic breakdown. All three forms of constipation are encountered in the elderly patient—hypertonic, hypotonic, and dyschezial ("rectal" or "habit" constipation). The hypotonic form is most common, as it also is among young children, although it is least common among young adults. Hypotonic constipation is characterized by late arrival of feces at every point along the colon, with diminished water absorption.