122 INFECTION AND IMMUNITY 



especially if this contains a certain amount of organic 

 impurities. It has been shown by experiment that it 

 will multiply abundantly in distilled water to which 

 from two to three per cent, of bouillon has been 

 added, also that it may preserve its vitality in steril- 

 ised well or river water for several months. Koch 

 found in his early investigations that rapid multipli- 

 cation may occur upon the surface of moist linen. In 

 a moist condition the cholera spirillum may retain 

 its vitality for months. It is therefore evident that 

 there is danger of its being carried to remote local- 

 ities in bed linen or underclothing soiled by cholera 

 discharges, if such articles in a moist condition are 

 packed up, without disinfecting, to be transported with 

 other personal effects of immigrants. Exposure to a 

 temperature of 140 Fahr. (60 C.) destroys the cholera 

 spirillum very promptly. It is also quickly killed by 

 desiccation and by exposure to direct sunlight two 

 to four hours' exposure. Experiments made in Dr. 

 Koch's laboratory show that it is killed in two hours 

 by sulphuric acid or hydrochloric acid diluted in the 

 proportion of one part to 1300 parts of water; by 

 carbolic acid 1:400 ; by lysol i : 500 ; by corrosive sub- 

 limate 1:10,000; by sulphate of copper 1:500. Solu- 

 tions of this strength would disinfect soiled linen, but 

 in practice it will be best to use the agents mentioned 

 in much stronger solutions one-per-cent. solutions 



