"Oh, I have some idea. Too many ideas in fact. Look, Johnson, chemistry's not your specialty but this is fairly elementary. All life contains protein, right?"
"Right."
"And all protein consists of amino acids. Every natural protein back home is built on levo—left turn—amino acids. Here it is just the opposite, the mirror image of what we know. Every amino acid is dextro—to the right!"
"But how can it be different here?"
"Johnson, they could ask the same question about us with equal justification—or, rather, equal lack of justification."
I was trying to feel my way through the confusion. "Barnes, I know a world could be made of anti-matter but—"
"No, no. Anti-matter is a reversal of changes within the atom. These atoms are the same as ours. It's the organization that is different—regular molecules with a different twist."
"But why should it have killed him then? We absorb starch and reject cellulose which is closely related. But the body just refuses to accept the cellulose. It doesn't necessarily go ahead and die."
"Starch and cellulose are both dextro, old man. This is a more fundamental difference. Maybe the body just throws off some of these compounds too. But there were some—plenty, I suspect—it couldn't throw off." He glanced toward the stiffening corpse, sympathetically.
"The poor kid couldn't leave well enough alone."