642 A MANUAL OF BACTERIOLOGY 



septic has been greatly discussed ; micro-organisms will 

 develop in nutrient media containing a considerable 

 proportion, but probably when in contact with living 

 cells a decomposition is effected, free iodine being liberated, 

 hence its value. 



The essential oils, peppermint, mustard, doves, thymol, 

 and menthol, are powerfully antiseptic. 



Disinfectant powders at best exert but a superficial 

 action. They act chiefly as deodorants, but may be useful 

 in preventing the breeding of flies in garbage, etc. 



It is useless to add a small quantity of disinfectant to a large 

 volume of fluid or solid ; the disinfectant must be added in sufficient 

 amount so that the mixture contains the minimum percentage 

 which has been found by experiment to be efficient. For this 

 reason the attempt to disinfect sewers, sewage, streets, etc., by 

 relatively small quantities of disinfectants is useless, and the money 

 so wasted would be far better employed in providing more water 

 for flushing purposes. 



In medical practice, while antiseptics can be applied locally with 

 success and, to some extent, for disinfecting the alimentary tract, 1 

 no substance has yet been discovered which can be administered 

 with safety to such a degree as to saturate the body, and so exert 

 a general germicidal action in bacterial infective diseases. Sal- 

 varsan, perhaps, to some extent possesses this power and has 

 been used with success in certain general infections, e.g. anthrax. 

 Protozoa are attacked selectively by many substances, e.g. the 

 malaria parasite by quinine, spirochaetes by salvarsan, trypano- 

 somes by atoxyl, trypan red, etc., Piroplasma canis by methylene- 

 blue, etc. 



In surgical practice no unbiased observer can doubt the efficacy 

 of antiseptic treatment, but many so-called " antiseptic operations " 

 are marred by faults of omission and commission which render 

 them far from being perfectly antiseptic. There has been some 

 controversy between the advocates of " antise : ptic " and of " aseptic" 

 surgery. Undoubtedly antiseptics do diminish the vitality and 

 therefore the reparative power of the tissues and aseptic methods 

 should so far as possible replace antiseptic ones. The skin of the 



1 See F. E. Taylor, "Intestinal Disinfection in Alimentary Toxaemia," 

 Medical Prets, January 14, 1914. 



