Avery,  MacLeod,  and  McCarty
   isolated  the  transforming principle by centrifugation to collect the
   cells, followed by heat-killing and extraction of macromolecules.

   This filtrate is capable of transformation.

   Inactivating  or  removing  the polysaccharides, proteins and RNA left
   the filtrate still capable of transformation.

   Adding  DNase  (an  enzume that digests DNA) to the filtrate stops the
   inactivated transformation, proving that the "active factor" is DNA.