THE MULTIPLICATION OF MICRO-ORGANISMS 255 



water bacteria present were reduced from 15483,000 to 

 62,445 in 1 c.c. at the end of twenty-four hours, whilst 

 after three days only 4,480 were found. Abel ^ states 

 that, when exposed to a temperature of —20° C, the 

 cholera bacilli may be destroyed after three days, and 

 with certainty after eight days. 



In connection with the exposure of organisms to 

 freezing temperatures, some investigations made by 

 Heyroth^ are of interest, although the medium em- 

 ployed was gelatine and not water. The organisms 

 were inoculated into gelatine tubes, and these were then 

 placed for some days in a freezing mixture consisting 

 of salt and snow. The temperature would be presum- 

 ably —20° C, certainly not below. As the inoculations 

 were made, with the exception of anthrax, from some- 

 what old cultivations, it is probable that in many cases- 

 spores were introduced. The gelatine tubes after being 

 removed from the freezing-mixture were incubated at 

 a suitable temperature, and subsequently examined to 

 ascertain whether growth had taken place or not (see 

 table on p. 256). 



Special investigations were made with the bacilli 

 and spores of anthrax, the former being obtained from 

 an animal just dead of anthrax. 



^ Gentralhlatt f. Bakteriologie, vol. xiv., 1893, p. 184. 

 ^ ' Ueber den Reinlichkeitszustand des nattirlichen und kunstlicheu 

 Eises,' Arheiten a. d. haiserlicJien Gesundlieitsamte, vol. iv., 1888, p. 1. 



