Whereas old dependency theory was Marxist in presentation, but nationalist in orientation, seeking to combine a theory of class struggle with a nationalist âthird worldistâ ideology, the new dependency theory is institutionalist in its analysis and political orientation.
Griffith concluded that the type II-R had been transformed into the lethal III-S strain by a transforming principle that was somehow part of the dead III-S strain bacteria. Today, we know that the transforming principle Griffith observed was the DNA of the III-s strain bacteria. While the bacteria had been killed, the DNA had survived the heating process and was taken up by the II-R strain bacteria. The III-S strain DNA contains the genes that form the protective polysaccharide capsule.
Griffith noticed that different strains of Pneumococcus could be cultured from one patient. He began to wonder if one strain could change into another. To test this idea, he did a series of experiments using the R and S strains. First, Griffith heated the S strain culture to kill the bacteria. As predicted, when injected into mice, the heat-killed bacteria did not produce an infection.