664 CONDITIONS AFFECTING THE DEATH OF FUNGI. 



pletely freed from all living organisms. It is much, 

 more difficult to kill quickly the spores of the mould 

 fungi. Hot air at a temperature of 120 C. does not com- 

 pletely destroy them after half an hour's exposure ; they 

 are not certainly killed unless they are exposed to a tem- 

 perature of 110 to 115 C. for an hour and a half. The 

 spores of penicillium appear to be less resistant than the 

 spores of Aspergillus niger. The most difficult to kill 

 are the spores of bacilli, although among these great 

 differences exist. Thus anthrax spores are less resistant 

 than the spores of tuhercle bacilli, and these again are- 

 less resistant than those of bacillus subtilis, and more 

 especially of the bacilli contained in garden earth, 

 influence of In the process of disinfection it is very important to 



moisture. 1,1,1 , -"-,-, 



remember that dry spores always require much longer 

 exposure to heat than spores in a moist state. It 

 appears as if that total alteration of the protoplasm 

 which leads to death occurs much more readily when 

 there is a certain amount of water in it than when it is 

 completely dry. Hence it is very difficult to destroy 

 the spores of bacilli by hot air ; even when a consider- 

 able amount of watery vapour is added to air kept at a 

 temperature of 100 to 140 C. it acts to a large extent 

 as a drying medium, and objects exposed to it rapidly 

 pass into such a state of dryness that it is only with 

 great difficulty that alterations of the protoplasm occur. 

 Thus the dry spores of bacilli are only killed by exposure 

 for three hours to a temperature of 140 C. If it is. 

 desired to disinfect the interior of large masses which 

 are bad conductors of heat, a much longer duration of 

 the heat is necessary in order to obtain the desired 

 effect. But even an exposure for three hours to 140 C. 

 irreparably spoils all sorts of clothing. 

 Action of heat it is much more easy to destroy the spores of bacilli 



in fluids. . J r . 



in fluids. Anthrax spores are destroyed in boiling 

 water - ithin two minutes ; the spores of the hay 

 bacillus resist this temperature for about ten or fifteen, 

 minutes (according to Buchner for sixty minutes) ; after 

 fifteen minutes the majority of spores are destroyed. 

 It is, however, often difficult to raise the temperature 



