In the wake of the stock market crash in October 1929, Thomas put his educational plans on hold and, through a friend, in February 1930 secured a job as surgical research assistant with Dr. Alfred Blalock at Vanderbilt University. On his first day of work, Thomas assisted Blalock with a surgical experiment on a dog. At the end of Thomas's first day, Blalock told Thomas they would do another experiment the next morning. Blalock told Thomas to "come in and put the animal to sleep and get it set up." Within a few weeks, Thomas was starting surgery on his own. Thomas was classified and paid as a janitor, despite the fact that by the mid-1930s, he was doing the work of a postdoctoral researcher in the lab.
