In order to work with a protein that was easy to obtain, we chose the protein lysozyme. (…) Fleming had shown that it occurred in tears and that egg white was also a rich source.
Our main target was egg white but we also tried human tears. Each morning when I came into the laboratory the assistant took a small sample of my tears. Not being an actor, I did not find it easy to weep at will, so my assistant would hold a slice of raw onion underneath one eye. I would hold my head to one side, to make it less easy for the tear to escape down the tear duct, and she would catch the tears with a little Pasteur pipette as they dribbled out of the other side of my eye. Even so, it was difficult to produce more that one or two tears, though I found it helped to think sad thoughts.
Francis Crick, from “What Mad Pursuit” (1988).