Mary Mergen was born in Tipton, Kansas, in Apr. 1895, and entered the Clyde convent in Nov. 1926. She was a sister to Sister M. Hildelita, who though younger had entered some years earlier. Both were half sisters of Mother M. Dolorosa. Sister's entrance was delayed because of caring for her aged father till his death. She was invested with the holy habit in Sept. 1927 and made her first profession on Sept. 8, 1928. Because of failing health her perpetual vows were postponed till 1934.

During her postulancy and novitiate she went by her confirmation name of Gertrude because there was another Mary in the group. She considered this a privilege and tried to imitate the great Benedictine mystic by the fervor of her life.

Sister was tall, with dark hair and deep-set blue eyes, quiet and gentle, charitable and thoughtful of others - an outstanding example of good zeal in every way. She loved prayer and was very careful about keeping silence at the prescribed times and places. She was an excellent seamstress and even as a junior novice made the postulants' dresses and investment veils. She also had an assignment at the Academy, teaching sewing and overseeing the girls' cleaning tasks. She had a gentle sense of humor which found expression in ingenious ways. 

While still a postulant she dressed a set of peanut dolls for one of Mother's feasts, naming them after the different terms of Gregorian chant: punctum, podatus, mora-vocis, torculus, etc.

Sister was never very robust and was sent to our Mundelein priory for a time for her health. After returning to Clyde she developed a painful type of pulmonary tuberculosis, and after months of bearing suffering and distress patiently, she quietly yielded her soul to God in the early morning of June 18, 1937, at the age of forty-one. Though her years in the convent were few, it was felt she had attained a high degree of virtue because of her great charity, her fervor and fidelity.