This term is being used all the time now, in the stories about Mad Cow. It's redundant, actually: meat IS muscle, just as tuna IS fish. The conflation of muscle with meat, probably the first time most people have actually confronted this fact, will erode meat-eating more surely than Mad Cow. It takes away the distancing so crucial to consuming animal parts.

On a related note, David Brown, a Washington Post staff writer who's also a medical doctor but, unlike "Lawrence A. Altman, M.D." of the New York Times doesn't broadcast the fact in his byline or stories, wrote the single best piece I've yet read in the mass media on Mad Cow. It appeared in Sunday's Washington Post.

What I found particularly riveting was this passage:

It is difficult to inactivate prions - much more difficult than it is to kill viruses, bacteria, or single-cell parasites. (Because prions are not alive, "killing" them is not quite the right term.) They can survive relatively high temperatures and caustic chemicals that leave other pathogens in pieces.

At one time, viruses were considered "in-between":not quite alive, yet not dead. Now come prions, not alive at all.

Looked at cybernetically (Claude Shannon, call your office), a prion is simply an instruction, or information. Bad news, that.