Cellular Divide: Harvested from embryos, stem cells may cure Alzheimer's, Parkinson's and a host of other diseases. But now the cells are at the heart of a war pitting pro-life purists against research.(National Affairs)

They're not much to look at, really. To see the cells of a four-day human embryo, you stain them with a few drops of dye, slip them under a 20- to 40-magnification microscope and peer through the eyepiece. There they are: a hollow sphere of roundish balls, snuggled up against each other like sticky blueberries, pollen grains or vibrant red raspberry drupelets (depending on which stain you used). The 40 or so cells that constitute the embryo look a little fuzzy, dusty even, as if they had been rolling around on a dirty floor. But that, of course, is only the beginning of what you see. If you are a passionate right-to-life activist, you see in the cells an incipient human life, one deserving all the rights and respect of any other human, chief among those the right not to be destroyed and not to be used as a means to an end. If, though, you suffer from a currently incurable disease like Parkinson's or Alzheimer's, or love someone who does, then those cells look very different: they look like the seeds of hope, tiny miracles able to dance on the head of a pin.

In those two clashing views lie the makings of the latest embryo war. This time, it's not about abortion: the embryos whose cells, called stem cells, hold the promise of treating often fatal illnesses come not from clinics where pregnancies end but from those where they begin: in vitro fertilization (IVF) centers, which fuse sperm with eggs in a petri dish, and where "spare" embryos, too numerous to implant in the womb of the would-be mother, are otherwise discarded. Even though stem cells do not come from aborted fetuses (which are defined as older than nine weeks, with a shape and incipient organs), the moral and theological issues inherent in using human embryos in research press the same hot buttons. As a result the White House, which hoped it had done its right-to-life duty by pulling financial support for organizations that offer abortion counseling overseas and by supporting every piece of pro-life legislation introduced in Congress, has been dragged into the heart of an issue it very much hoped to avoid.

Sometime in the coming weeks, President George W. Bush is expected…