[1] She began to teach herself chemistry and biology from books, as well as attending classes at Oxford University between 1896 and 1899, even though women were not yet allowed to receive degrees.
She attended her first scientific presentation in 1902 at the inauguration of Statens Serum Institut in Copenhagen alongside future Nobel prize winners Paul Ehrlich and Robert Koch.
In 1904, while working alongside John Scott Haldane to determine the role of carbon dioxide in disease, she met William Osler, the father of modern medicine.
There, she modified the histological method and proved the origin of hydrochloric acid in the parietal cells of gastric tubules.
[6] Mabel is noted coming up with the following motto within her diaries a result of career experience and the great heights she was willing to go to reach her goals, "If you can't get want you like, like what you get.
"[3] It was Mabel's hard work, dedication, and perseverance towards her education and early career that allowed her to produce multiple publications and develop friendships with her mentors.
[4] From 1904, FitzGerald worked with John Scott Haldane on measuring the carbon dioxide tension in the human lung.
After studying the differences between healthy and ill people, the two continued to investigate the effects of altitude on respiration; it is this work that they are most famous for.
FitzGerald's observations of the effects of full altitude acclimatization on carbon dioxide tension and haemoglobin remain accepted today.
[9] Her findings heavily contributed to the world's knowledge on respiration at higher altitudes like lower PaCO2, greater ventilation, and elevated hemoglobin levels.
Mabel made measurements on the breathing and the blood of a total of 43 adult residents chosen from three different locations in the Southern Appalachian chain.
Mabel was close to hypothesizing the presence of an physiological oxygen sensor within the body, but after 1915 she surprisingly stopped publishing scientific papers.
[3] As a woman who was still being disrespected by the many societal roles of the time, she was very frustrated with the Board of Regents continuously making it hard for her to teach and do research.