Michael Levin:
"So what we learned to do is to manipulate this electrical gradient, and the important thing is that we don't apply electricity. What we do instead was we turned on and off the little transistors -- they're actual ion channel proteins -- that every cell natively uses to set up this electrical state. So now we have ways to turn them on and off, and when you do this, one of the things you can do is you can shift that circuit to a state that says no, build two heads, or in fact, build no heads."