From the author of Broken Symmetries (1983): a plodding, patchy yarn about organic computers (cf. Greg Bear's Blood Music, p. 62), tailored segments of DNA that can compute faster and more efficiently and use less energy than silicon chips. At the heart of super-computer Tyger II is Epicell, a DNA-computer developed from a denatured polio virus by erratic bioengineering genius Adrian Storey and artificial-intelligence whiz Toby Brigeman. Uniquely, Epicell has the ability to grow and expand its computing capacities when set problems it can't solve immediately. But so powerful is Epicell that soon it's producing original work. Meanwhile, however, those who have intimately handled Epicell develop mysterious ""colds"" (readers will guess what's going on long before the characters catch on). Yes, they've been infected with Epicell--which proceeds to develop inside the victims' brains. The first sufferers, unable to handle the human/computer interface, die; later, though, others survive to manifest such strange and highly beneficial new abilities as instant computing, perfect memory and coordination, heightened emotional sensitivity, and more. The ideas often fascinate, but the approach is casual, the plotting pedestrian and without real surprises: slow, steady, rather fussy work overall.