Herter returned to his alma mater in 1903 as Professor of Pharmacology and Therapeutics. It was during this time that he researched diseases of the gastrointestinal tract. His work on celiac disease, which he called "intestinal infantilism", led to the eponym Gee-Herter disease. His important contribution was to highlight the retarded growth of affected children. Herter's theory as to the cause – that it was due to overgrowth and persistence of gram-positive bacterial flora normally belonging to the nursling period – failed to gain acceptance. However, he did correctly identify that any "attempt to encourage growth by the use of increased amounts of carbohydrates" led to relapse. This would later be discovered to be due to the gluten content of wheat.