THE OUTLOOK FOR THE FUTURE 265 



and even fewer crystallized, it is already well established that we are 

 dealing here with a great variety of chemical compounds. It is sufficient 

 to mention the polypeptides (tyrothricin), oxidation-reduction systems 

 (pyocyanin, actinomycin), sulfur compounds (gliotoxin), quinones 

 (citrinin), various other non-nitrogenous simple (clavacin) and more 

 complex (fumigacin) compounds, a variety of nitrogenous compounds 

 comprising both bases (streptothricin, proactinomycin) and acids (peni- 

 cillin). Compounds, like actinomycin, that are highly active against bac- 

 teria but also highly toxic to animals, may possibly be modified in such a 

 manner as to reduce their toxicity without impairing their activity. This 

 is also true of simpler compounds, such as the less toxic but also less ac- 

 tive clavacin and gliotoxin. Many a chemist is awaiting the solution of 

 the problem of the chemical nature of penicillin before beginning new 

 syntheses. 



Doubtless most of the compounds that prove to be useful as chemo- 

 therapeutic agents will sooner or later be synthesized. The contribution 

 of the bacteriologist may be all but forgotten in the light of the forth- 

 coming chemical developments, but even the bacteriologist will be 

 grateful for new tools to help combat disease-producing agents. 



THE FIELD OF CHEMOTHERAPY 



The utilization of the activities of antagonistic microorganisms for 

 the control of human and animal diseases has only begun. The same 

 may be said of the control of plant diseases. Many practices in surgery 

 and many old-time remedies are based on the creation of conditions fa- 

 vorable to the development of antagonistic microbes. Consider, for ex- 

 ample, the method of cast surgery developed during the Spanish Civil 

 War. To what extent the application of pure cultures of antagonists 

 may improve these and similar practices still remains to be determined. 

 Plaster treatment of wounds, without the use of antiseptics, has often 

 given marvelous results. Such wounds have been found to contain 

 aerobic bacteria with no one group predominating, except that Ps. aeru- 

 ginosa tends to become more numerous when the healing process has 

 been established (889). It still remains to be determined whether this 

 organism exerts a favorable effect due to its antagonistic properties or 

 is only another wound-infecting agent. 



