NATURE OF ANTIBIOTIC SUBSTANCES 115 



in Table 2 1 . The organism produces dark-brown to black pigments on 

 media containing protein and peptone. It is not affected by heat. It is 

 soluble in ether and in alcohol as well as in other solvents, but in water 

 only in very high dilutions. It is highly toxic to animals. Actinomycin 



TABLE 21. BACTERIOSTATIC SPECTRUM OF ACTINOMYCIN 



From Waksman and Woodruff (946). 



Note, o indicates no growth; I, trace of growth; 2, fair growth; 3, good growth. 



* rf 200 mg. per liter were added the results were usually as follows: for A. aerogenes, fair; for 



E. coli (intermediate), trace; for E. coli, no growth. 



