Oswald Avery and others have continued Griffth’s transforming principle to prove DNA as genetic material . Substantiate.

Explanation

Griffith - Experiments rough and smooth strains of Streptococcus pneumoniae.
S- Strain - injected to mice - mice die
R- Strain - injected to mice - mice alive
Heat killed S-Strain injected to mice did not kill them
Heat killed S- Strain mixed with R-strain injected to mice they died
R strain of bacteria transformed by heat killed S- Strain become virulent but biochemical nature of genetic material not defined- some transforming principle transformed from heat killed S-Strain.
Oswald Avery and others worked to determine biochemical were nature and transforming principle proteins, DNA, RNA from heat killed s-cells were purified and discovered that DNA alone from S-bacteria cells caused R bacteria to become transformed.
Protein digesting proteases, RNA digesting RNases did not affect transformation, transforming substance was not protein or RNA. DNase did inhibit transformation, suggesting that DNA caused transformation and DNA is the hereditary material.