Professor Buchannan suffers from the liver disease called, cirrhosis.
Cirrhosis is a condition involving heavy scarring of the liver caused by chronic conditions and diseases, such as heavy alcoholism and hepatitis. All these chronic damages cause serious problems on the functioning of the liver. Throughout the years, professor's liver tried to repair itself from the damages and that is why the scars were formed.
Vestigial because they don't use it but it's still there
