摘要：

Our results can be explained if the following assumptions are made: 1. (1) that during their growth in an appropriate medium pneumococci go through a period of about 15 minutes or less ("competence") during which they are able to absorb various large molecules such as desoxyribonucleic acid (DNA) and desoxyribonuclease (DNase). 2. (2) that the transformation may be produced by the penetration into a "competent" bacterium of one particle of DNA carrying the new character. 3. (3) that the transforming DNA stays accessible for a time to the DNase even after its entrance into the "competent" bacterium. The transforming DNA absorbed by the bacterium is protected against the action of the exogenous DNase when the bacterium has lost its "competence" ( i.e. its permeability to large molecules) and probably before the integration of the transforming DNA into the bacterial genome.

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