SELECTED PAPERS 



rial toxins in a pure and crystalline state is certainly one of the most 

 remarkable biochemical achievements attained in recent years. The 

 establishment that the toxin of Clostridium botulinum Type A is a protein 

 of high molecular weight, containing amongst others all ten amino- 

 acids essential for animal nutrition, is extremely surprising in view of 

 the almost incredible toxicity of the product. The fact that one micro- 

 gram of such a protein has the potency for killing 20,000 mice is one 

 of the most startling physiological effects known, and is still awaiting 

 explanation. 



The quantities of antibiotics needed to attain a definite bacteri- 

 ostatic or bactericidal effect, though small, are large when compared 

 with the quantities of toxins needed for their action. 



It is not, therefore, the low doses required for a noticeable activity 

 of the antibiotics which makes them so remarkable and such mighty 

 tools in human therapy, but their amazing specificity. It is not so sur- 

 prising that some hundredths of a microgram of penicillin per millilitre 

 medium inhibit the development of many bacteria, as the fact that 

 this antibiotic even in much higher concentration does not have any 

 harmful effect on many other bacteria] species or on the body cells of 

 man and animal. 



Some time ago the General Assembly of the United Nations spec- 

 ified and condemned the crime of 'genocide' or 'race discrimination 

 in murdering' ; it is very obvious that in the microbe world either 

 such laws do not exist, or that microbes are far from being law-abiding 

 creatures. 



The discovery of the various antibiotics like penicillin, strepto- 

 mycin, chloramphenicol, aureomycin, terramycin and bacitracine has 

 created a mighty microbiological industry in which either moulds, 

 actinomycetes or bacteria are cultivated on a huge scale. If one tells 

 a layman that the world production of penicillin for 1950 - and also 

 that of streptomycin - was about 150 tons he will probably not be 

 much impressed. But as soon as one can make him realize that for 

 each of these products 30,000,000 gallons of culture media have been 

 prepared, inoculated and harvested, a new light will be thrown on 

 this tremendous achievement of our industrial microbiologists. 



Of course, even this statement does not do justice to the accomplish- 

 ments of the microbiologist. Before any industrial production of an 

 antibiotic, thousands of micro-organisms may have been isolated from 



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