The Effect of Chetnicals on Microorganisms 197 



6. Fungicide: An agent which destroys fungi. 



7. Sterilization: The act or process of freeing something of all 

 living cells— plant and animal, microscopic and macroscopic. 



8. Chemotherapy: The treatinent of infectious diseases with sub- 

 stances which kill or inhibit the growth of pathogenic organisms 

 in the host's body without causing serious injury to the host. 

 This term dates to the early 1870's when Weigert applied ani- 

 line dyes for tissue staining, and Ehrlich began considering the 

 use of dyes in vivo (in the body) as bactericidal substances. 

 Ehrlich introduced the term chemotherapij when he discovered 

 "606," the synthetic, arsenic-containing aniline compound used 

 for the treatment of syphilis. 



Some chemicals that exert powerful destructive action on mi- 

 croorganisms may, in lower concentrations, exhibit a stimulatory 

 effect on these same organisms. Disinfectants may act as anti- 

 septics or as bacteriostats at different concentrations, and in very 

 dilute amounts these same compounds may actually stimulate 

 microbial growth. 



CHARACTERISTICS OF AN IDEAL DISINFECTANT 



There is no such thincr as an ideal disinfectant on the market 

 todav. If you were given the task of trying to design such a com- 

 pound, the following minimum considerations would have to be 

 fulfilled: 



1. High Germicidal Power. The word germicide is used here 

 rather than bactericide because an ideal disinfectant should have 

 a wide killing range with respect to microorganisms. The chances 

 of finding a pure microbial culture in the area to be disinfected are 

 rather remote. Therefore, any chemical aimed at freeing an area 

 of infectious agents should be sufficiently broad in its killing power 

 to give reasonable assurance of success. 



2. Stability. If the chemical has strong affinity for all kinds of 

 organic matter, the disinfectant may be dissipated before it has had 

 an opportunity to combine with and to destroy microorganisms. 

 Organic matter must be anticipated in the locations where disin- 



