Problem:

Using a combination of extraction and enzymatic degradation
techniques, Oswald Avery and colleagues demostrated that DNA was
responsible for transforming Streptococcus pneumoniae from
the avirulent type R strain to the virulent type S strain. Explain
why this experiment was insufficient to demostrate that DNA
molecules carry genetic information from generation to generation
during normal inheritance.

It would help me a lot if someone can come to an answer. Thank
you!