I miss having my granddaughter in residence... well, most of the time. Tonight, however, a rainy and humid evening, I was actually glad she was back home in New Hampshire so I wouldn't have to show her something remarkable... and remarkably complicated. I'd seen the two slugs gliding up the basement storm-door glass, but thought little of it, save that here were yet more of the shell-less gastropods bound and determined to make life difficult for our garden plants. But when I came back downstairs an hour or so later, well, the mollusks were intertwined and had clearly taken a shine to each other. Slugs are hermaphrodites, and a number of species don't need a mate with which to carry on the line. These, however, felt the need for a partner and, their penises somewhere linked, were busy exchanging sperm that would, in short order, be taken into the vaginas of the other partner. The entire process is messy, miraculous, and a challenge to explain: the toughest part when the perceptive innocent wants to know if mommy and daddy, um, we'll leave it at that.