158 BACTERIOLOGICAL CHEMISTRY 



tlieriiiosiable. It is very strongly bacteriostatic to iriaiiy 

 Gram -positive organisms even at a dilution of 1 in 10^. 

 Gram -negative bacteria are usually less sensitive (dilu- 

 tions of 1 in 5000 to 1 in 10^ being necessary for bacterio- 

 stasis) but there is no clear dividing line. It is only 

 slowly bactericidal. Actinomycin A inhibits the fibrino- 

 \ytic activity of cultures or filtrates of hsemolytic strepto- 

 cocci and the coagulase activity of staphylococci. It is 

 highly toxic to animals, when injected intraperitoneally, 

 intramuscularly or intravenously. 



Actinomycin B is a colourless compound which is 

 only slightly bacteriostatic but highly bactericidal to 

 Gram -positive organisms at concentrations of 1 mg. in 

 100 ml. Gram-negative bacteria are more resistant. It 

 is also highly toxic to animals. 



Actinomycin B predominates in young cultures of 

 A. antibioticus and Actinomycin A in old cultures. 



Aspergillic Acid. — Aspergillus f lavas, when grown as 

 a surface culture on a peptone medium gives yields of 

 250 to 400 mg. of crystalline aspergillic acid per litre of 

 medium. Aspergillic acid is a monobasic, amphoteric 

 acid, C12H20N2O2, m.p. 93°C., [a]D+14°. It can be dis- 

 tilled in steam or in vacuo without loss of activity and 

 is stable to acid and to alkali. When grown on a peptone 

 medium containing 2 per cent, of brown sugar A. flavus 

 gives a closely related substance, C12H20O3N2, containing 

 one oxygen atom more than aspergillic acid, and having 

 m.p. 149°C, [ajo + 42° and about one tenth the activity 

 of aspergillic acid. The substance isolated by Glister 

 from a species of Aspergillus related to, but not identical 

 with A. flavus, active against Esch. coli, Eherthella 

 typhosa. Salmonella paratyphi, Sal. schottmillleri, Shigella 

 dysentericB and Vibrio comma, as well as against Gram- 

 positive organisms, at a dilution of one in 200,000 is 

 aspergillic acid. It is bacteriostatic to Gram-positive 

 and Gram-negative bacteria, e.g., streptococci, staphylo- 

 cocci, pneumococci, Esch. coli, Aerobacter aerogenes, in 



