I, —PHYSIOLOGY. 175 



Ethyl hydrocupreine Iso-octyl hydro- 



(optoquin) cupreine {vuzin) 



Diphtheria bacillus . . . . 1 in 100,000 . . 1 in 750,000 



Pneumococcus .. . .• 1 in 400,000 .. Negligible 



Staphylococcus . . . . 1 in 500 . . 1 in 16,000 



Streptococcus . . . , 1 in 1,000 . . 1 in 80,000 



The action of optoquin on the pneumococcus and of vuzin on bacillus 

 diphtheriae is highly specific ; the higher and lower homologues have a 

 greatly diminished effect. Many substances destroy bacteria in the test 

 tube, but these drugs act in the animal body as well as in the test tube, 

 and enough can be given by medicinal doses to animals and men to render 

 the blood of these animals bactericidal. 



The second group of drugs which exert a marked action on bacteria 

 are certain derivatives of acridine. Trypaflavin was used during the war 

 for infected wounds : unlike most antiseptics it acts better in the presence 

 of protein, but is not sufficiently selective or specific on micro-organisms 

 in the presence of body tissues to be of any real value ; it is easily absorbed 

 and readily causes oedema. Rivanol is a more recent derivative of 

 acridine. Morgenroth cured streptococcic infections by injections of 

 rivanol under the skin. The injections to be efl&cient must be made soon 

 after the infection and in the neighbourhood of the inoculated zone ; 

 rivanol will not cure a blood infection. Its discovery is, however, a great 

 advance over any substance previously available in this group, and we 

 can anticipate with some confidence in the near future the introduction 

 of other derivatives which will destroy acute infective agents. 



Two other chemical substances are worthy of consideration for the 

 remarkable effects accredited to them in the treatment of microbial 

 infections. Mercurochrome, a dyestuff, is a combination of mercury 

 with dibromo-fluorescein : 



H„OH 



Mercurochrome 



C.H..CO,Na 



After injection it is excreted by the urine and bile, yet neither the 

 urine nor bile exhibits bactericidal properties. Nevertheless, clinical 

 evidence shows that it exerts a curative effect, especially in the case of 

 streptococcic and staphylococcic infections, and these effects have been 

 repeated in animal experiments. 



Hexyl Resorcinol is a representative of another group of substances. 

 The introduction of an alkyl radical into resorcinol diminishes its toxicity 

 to tissues, but increases its bactericidal properties. 



OH 



Alkyl Resorcinol 

 'OH 

 R 



U. 



