ANTISEPTICS 169 



ruvate, but no concentrations are mentioned in their very 

 brief abstract. 



The experiences of Gardner and of Eagle mentioned 

 above leave little doubt that the mechanism of cell divi- 

 sion is affected by concentrations which interfere neither 

 with growth nor with motility. 



Multiplication curves of bacteria in presence of peni- 

 cillin were studied by the writer who measured neophelo- 

 metrically the retardation of multiplication with several 

 types of bacteria. No definite increase in the lag period 

 could be observed, and all retardation seemed to be due 

 to a decreased growth rate (Table 35). Streptococcus 

 lactis in presence of 10 ppm. penicillin never multiplied 

 enough to increase the turbidity 10%. The final crops 

 show the usual decrease with increasing antiseptic con- 

 centration (except wdth 5 ppm. where multiplication for 

 the first 3 days was in conformity with that of the other 

 cultures, while its velocity increased on the fourth day; 

 the increase could not be traced to a contamination). 



From these growth studies, the action of penicillin 

 seems to be identical with that of many antiseptics. 

 Penicillin does not act like a dye nor like a sulfonamide. 



The understanding of the nature of the penicillin effect 

 is complicated by the fact that at least two different bac- 

 tericidal substances are produced by the mold. Besides the 

 true penicillin, a penicillin 5 has been isolated by Rob- 

 erts et al. (1943), while Kocholaty (1942) discovered a 

 substance called penatin, and Coulthard et al. (1942) 

 found an enzyme which they called notatin. This en- 

 zyme is an aerobic dehydrogenase oxidizing glucose to 

 gluconic acid with the simultaneous production of HoOo. 

 Birkinshaw and Raistrick (1943) assume that penicillin 

 B, penatin, and notatin are the same substance, which 

 acts simply by gradually accumulating an inhibiting 

 amount of HoO^. This substance may completely inhibit 

 multiplication in a dilution of 1 part in a billion, but only 

 when glucose and oxygen are present, and catalase absent. 



