In the light of Griffith's experiment , explain the action of two strains of Diplococcus pneumoniase and give his conclusion .

Explanation

The first series of experiments were performed by a British physician , F. Griffith in 1928 , using the bacterium Diplococcus pneumoniae which causes pneumonia in mammals . There are two types of strains S - type and R - type .
(i) When R - strain injected into mice , mice survived .
(ii) When S - strain injected into mice , mice died .
(iii) When heat killed S - type injected into mice , the mice survived .
When heat killed S - type and R type injected into mice, the mice died .
Conclusion : (a) R-type is rough type and it is avirulent .
(b) S - type is smooth type and it is virulent .
When blood sample from dead mice was cultured, colonies of living S - type were obtained . Griffith concluded that living R-type of bacteria must have picked up something from surrounding medium that contains heat killed S - type and got changed into type . This change is due to the phenomenon other than mutation , which he called transformation .