They were also able to determine that the structure could only have two, three, or four strands, as the X-ray data indicated. Numbers greater than four were implausible due to the angles and radii at which the strands must bend. However, it soon became clear that these Mg++ bonds could not function due to the presence of water in the structure. After this first attempt at a model, Watson began studying tobacco mosaic virus, because most of it was made up of nucleic acid and could potentially give him insight into DNA. Additionally, TMV's acid was RNA, which not only could help him understand DNA, but was also unclaimed scientific territory. His major breakthrough came when he made an x-ray that clearly showed the helical structure of RNA in TMV. This strongly supported his argument against Rosy, who insisted that DNA could not be helical. After a long series of unsatisfactory discoveries, Watson began research into the sexual relationships of bacteria. He discovered evidence of the distinction between male and female bacteria and studied mating habits. This observation of