266 THE OUTLOOK FOR THE FUTURE 



Of particular importance is the development of the manufacture of 

 antibiotic substances. Largely because of the stimulus given by World 

 War II when the need for new antibacterial agents became very acute, 

 an intensive study was made of the practicability of utilizing some of 

 the agents already known, and search was made for new ones. Among 

 these, penicillin occupies a leading place. As these lines are written, a 

 large number of great concerns in this country, in Great Britain, and 

 elsewhere are engaged in the manufacture of this drug by utilizing 

 several strains of P. notatum and P. chrysogenum. An intensive search 

 is being made for new agents capable of inhibiting the growth of and 

 destroying other pathogens resistant to the action of penicillin. 



The progress made in the isolation of antibiotic substances from many 

 microorganisms has not kept pace with their evaluation as chemothera- 

 peutic agents. In discussing antimicrobial agents of biological origin, 

 Dubos (189) emphasizes that students of infectious diseases are pri- 

 marily concerned with the action of these substances upon certain strains 

 and stages of the parasites, with the mechanism of their action upon the 

 susceptible cells, and with physiologic and pathologic effects on the host. 

 Mcllwain (560), on the other hand, believes that animal testing in 

 chemotherapy is not necessarily much nearer to the conditions under 

 which the drug will be finally used than are properly chosen in vitro 

 conditions j although in vitro testing does not reproduce all the condi- 

 tions of the normal environment of the parasite, it is less likely, under 

 present conditions of testing, to introduce new and unknown factors 

 than is testing in another host. The in vitro and in vivo studies of an 

 agent are considered as complementary. 



The utilization of fungi and bacteria against plant diseases has also 

 been variously attempted (472). The main difficulty involved is to es- 

 tablish the antagonist in the soil. This can be done by modifying soil 

 conditions, as by the addition of stable manure or other plant and animal 

 residues, in order to favor the development of the antagonist. 



The activities of antagonistic microorganisms are also utilized for 

 combating injurious insects and other lower animal forms destructive to 

 plants and to animals. Among the insects, the Japanese and other 

 Asiatic beetles have been treated rather successfully by the use of nema- 

 todes and certain specific bacteria. Extensive use has already been made 



