Among the wizardries of the newer pleomorphic bacteriology, none are of greater interest than the recent test-tube syntheses of what may be described as composite pneumococci. The burbankian magic at the Rockefeller Institute of grafting an alien capsule on a naked bacterial cell may not be of immediate practical interest, but it may serve as an introduction of clinical medicine to the complexities in this field.
It is now apparently confirmed that if pure cultures of virulent type pneumococci are grown under certain suboptimal conditions they "dissociate" into mixed cultures of two or more different morphologies, specificities, virulences or cultural characteristics. An avirulent, non-type-specific, noncapsulated pneumococcus "mutant," for example, is readily produced. This naked "involution form" is apparently incapable of forming the type-specific capsular polysaccharide and breeds true as a noncapsulated entity for innumerable test-tube generations. Four years ago, Griffith1 injected this naked "degenerate" of known ancestral type-specificity subcutaneously