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1,291. Some germs e.g., the germs of putrefaction, 

 are only saprophitic and not parasitic, They flourish best 

 at the temperature of 75 to 85F., while parasitic miscrobes 

 grow best with a temperature of 98 to io4F., i.e., the tem- 

 perature of the animal body. Most microbes stop growing 

 below a temperature of 48F., and a few are destroyed by 

 freezing, though the majority of microbes only remain quies- 

 cent at low temperatures and do not actually lose their 

 vitality. Under repeated thawings and freezings they suc- 

 cumb more quickly. But spores of anthrax survive even 

 this treatment. In the sporular condition, microbes stand 

 high temperatures also much better, though most of them 

 lose their vitality in their vegetative condition subjected for 

 ten minutes to the dry heat of i2oF. They can stand 

 moist heat better than dry heat, and if it is intended to des- 

 troy microbes by the use of hot water, or by heating milk 

 or other liquids which are likely to contain microbes, it is 

 necessary to bring up the temperature to i5oF. Some 

 microbes which live in the soil can resist the temperature of 

 even i65F. Parasitic microbes are more readily killed by 

 heat than saprophitic microbes, and the action of disinfectants 

 in killing the former is much enhanced if they are applied 

 hot. Dr. Heider of Berlin showed how the spores of anthrax 

 resisted the action of a 5% solution of carbolic acid for 36 

 days in the ordinary European temperature, but the solution 

 raised to a temperature of i25F., was sufficient to kill the 

 spores in a few hours. That weak disinfectants are more 

 effective when tliey are used hot, is a fact of great economic 

 importance. Soap is a weak disinfectant, but hot soap water 

 is a very effective substance to use for washing soiled clothes, 

 etc. Saprophitic germs must be subjected to a heat of 25oF., 

 for 10 minutes before they are killed. In the ordinary boil- 

 ing temperature of water it requires 6 hours to kill somenof 

 the spores of putrefactive germs. Exposure to heat not 

 sufficient to kill disease producing germs may yet attenuate 



