ROOM DISINFECTION. 529 



Repeated cultivation of an organism, g'eneration after 

 generation, in the presence of an antiseptic such as carbolic 

 acid will result in a more or less profound alteration of the 

 physiological properties of the organism. Thus, when the 

 anthrax bacillus is grown at 32° in veal bouillon, contain- 

 ing variable amounts of phenol (from 1: 500 to 1: 5,000) and 

 transplantations are made every 8-10 days, the sporeless or 

 asporogenic modification will be obtained. If a similar culti- 

 vation is carried on at 42.5° not only is the sporeless variety 

 obtained, but this is also deprived of its virulence. In other 

 words, the antiseptic acting at a higher temperature in- 

 duces more marked alterations than at a lower temperature 

 and hence give rise to sporeless, attenuated cultures. The 

 asporogenic characteristic is permanent on ordinary media 

 but the spore production is said to return after cultivation 

 on peptonless agar. 



Similar modifications are obtained by growing motile 

 bacteria in media containing carbolic acid. Thus, the 

 Eberth .and colon bacillus will lose their motility, when 

 carried through several generations at 39°, in bouillon con- 

 taining about 1 : 3000 of carbolic acid. 



Room Disinfection. 



In this laboratory a special room is provided having a 

 capacity of 1,016 cu. feet (28.8 cu. m.) in which gaseous dis- 

 infectants may be tested. The gaseous compounds com- 

 monly in use at the present time are sulphur dioxide and 

 formaldehyde. > 



The sulphur, either in the form of flowers or in rolls, is 

 placed in an iron water-bath which is set over a large pan 

 of water. 3 pounds of sulphur per 1,000 cu. feet are ordin- 

 arily employed. To this amount, 50 c.c. or more of alcohol 

 are added and this is then set on fire. The specimens have 

 previously been arranged in the room, under the desired ex- 

 periinental conditions. All cracks about the door and win- 



34 



