SELECTED PAPERS 



horrifying monstrosities. The biologist of today in his creative powers 

 still ranks far below the votaries of what Stapledon has called the 

 'vital art', but this does not alter the fact that the microbiologist has 

 already succeeded in producing artificially numerous micro-organisms 

 with quite new property complexes. With the aid of x-rays, ultra- 

 violet radiation, neutrons or of chemical agents it has been possible 

 to bring about radical changes in the wild forms, and many of the 

 mutants thus obtained are characterized by a great stability. Although 

 in most of the cases these mutations will be due to the loss of some 

 genetic unit, the result may be quite beneficial to the industrialist. It 

 is well known that the said procedures have already led to a hundred- 

 fold - or even still higher - increase in yield of penicillin, strepto- 

 mycin and other metabolic products. 



Beadle and his co-workers have further shown that new forms of 

 life may be obtained by applying mutant forms of moulds in hybridi- 

 zation experiments, and Tatum and Lederberg have arrived at the 

 unexpected conclusion that the same should be possible for bacteria. 



Finally, it is difficult to overrate the importance of the investigations 

 of Avery and McCarty which brought conclusive proof that the 

 genetical apparatus of a bacterial cell can be reinforced by purely 

 chemical means. Addition of 0.003 microgram of a desoxyribonu- 

 cleinic acid preparation, isolated from capsulated pneumococcus cells, 

 to the culture of a capsule-less variant sufficed to bring about a per- 

 manent restoration of the ability to form capsules in this variant. It is 

 tempting to connect these observations with the virus problem and 

 to conclude that a time may arrive at which, besides virus diseases, 

 virus cures will be known, implying the industrial preparation of 

 various specific desoxyribonucleinic acids. 



In any case, it seems certain that the microbiological industry of 

 the future will be a 'key-industry' which will produce and deliver the 

 micro-organisms with optimal properties for technical application. 



In concluding I should like to express the hope that the foregoing 

 bird's-eye view of the relations between the microbe world and in- 

 dustry will have convinced you that microbial metabolism has, in- 

 deed, multifarious industrial implications. 



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