l60 THE CYTOLOGY AND LIFE-HISTORY OF BACTERIA 



types of capsular material, in the pneuniococcus. If a non-capsulated strain 

 is brought into contact with a deoxyribose nucleic acid derived from a strain 

 of different antigenic structure, it will commence to produce the capsular 

 material appropriate to the strain from which the nucleic acid is derived, 

 irrespective of the antigenic type of the capsule which it originally possessed. 

 The genetic material, in this case, may be nuclear in origin, or may be the 

 surface, secretory material of the cell, which is capable, as enzyme systems in 

 other cells have been presumed to be capable, of reproducing itself without 

 reference to the genetic constitution oi the nucleus. 



Mutations in the power of resistance to antibacterial agents, and in 

 bacteriophage sensitivity, have both given evidence of a genetic system 

 resembling that of higher organisms. There is, in fact, little to suggest that 

 the entire, complex pattern of bacterial dissociation may not be explicable 

 in terms o( multiple and interrelated gene changes. 



C; SUMMARY 

 The cytological evidence, presented in this work, is confirmed by genetical 

 evidence. 



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