1.   --Bauer failed to disprove the possibility of impropriety.

2.   Disproving that possibility, though, will be nearly impossible, so xenotransplants will always involve some apprehension and controversy.

3.   It neither proved nor disproved the possibility of successful electronic publishing over the Web.

4.   The tests do not conclusively disprove the possibility, however, because other vaccines for which samples were not kept could still have been made from chimpanzee cells.