Introduction. "Dominant Species" began as a chapter in another longer work. As the original story evolved, however, the chapter's "bug" theme did not fit and was set aside. Much later, while researching information on a different idea, I came across an article about porphryin, which has an interesting property in that it tends to look for and bond with cancer cells. When the chemical is irradiated, cancer cells "marked" with porphryin glow under laser or ultraviolet light. Scientists hope that this chemical marker, combined with a chemical "bullet," can be used to search for and destroy cancer cells. The "marker" triggered an idea that fit into the shelved chapter, and that chapter grew into this story. "Dominant Species" was the first story I got a paycheck for.