nelson: screening methods in microbiology 335 



how to avoid confusion of hereditary changes with physiologically 

 induced morphological changes as the culture ages. 



Langham: You defined potency as yield. If you consider potency for 

 potency's sake, it is known that the potency of insecticides, such as 

 pyrethrum, can be increased about 100 per cent by the use of synergids. 

 This was discovered during the last war when sesame oil was used in 

 aerosol bombs. Chemical tests showed that both sesamin and sesamolin 

 were responsible for the observed synergism, and further that the meth- 

 ylenedioxyphenyl group of these compounds was the effective one. Later, 

 other compounds with this same group proved effective and are now 

 used in commercial insecticides. (These are piperonyl butoxide, sulf- 

 oxide, etc.) Have these chemicals been tested for a possible synergistic 

 effect on antibiotics? 



Nelson: Those specific compounds have not been tested and I suspect 

 that they would be too toxic for intravenous administration. However, 

 a large part of clinical research concerns synergisms and antagonisms 

 between different antibiotics and potentiating effects of derivatives upon 

 antibiotic effectiveness. 



