Answer:
The tests on the purified substance revealed that it contained high levels of phosphorus and very little sulfur. This finding was significant because DNA contains high levels of phosphorus but very little sulfur, while proteins contain high levels of sulfur but very little phosphorus. This data further supported the hypothesis that DNA was the transforming factor, as it suggested that the substance being studied was DNA rather than a protein. This was because the levels of phosphorus found in the purified substance were consistent with what would be expected from DNA, while the levels of sulfur were not consistent with what would be expected from a protein. Therefore, the data from the tests on the purified substance provided strong evidence that DNA was the transforming factor.