For a long time Becker's book was about the only thing out there: "The Body Electric: Electromagnetism and the Foundation of Life" by Robert O. Becker https://en.wikipedia.org/wiki/The_Body_Electric_(book)
Now there's pretty serious progress being made at Levin's lab: "What Bodies Think About: Bioelectric Computation Outside the Nervous System" talk by Michael Levin https://www.youtube.com/watch?v=RjD1aLm4Thg https://news.ycombinator.com/item?id=18736698