456 DESTRUCTION OF TYPHOID AND COLON BACILLUS. 



for months lias little effect on the vitality of the typhoid or of the 

 colon bacillus. To determine the influence of desiccation upon these 

 organisms, and also upon the stai)hylococcus aureus, the following 

 exi)eriments were made : 



Bouillon cultures of the bacillus typhi abdominalis, the bacillus coli 

 communis, and the stai^hylococcus aureus were roughly dried on threads 

 1 cm. long and then desiccated, a i)ortion being i)laced in a vacuum, 

 another portion in a desiccator over sulphuric acid, and a third in a 

 closet; all were kept in the dark. The result of the desiccation under 

 the three ditferent conditions is as follows: 



Bacillus typM abdominalis. — Lived in a vacuum from December 30 

 until July 24, or 207 days; in a desiccator over suljjliuric acid from 

 January 3 until July 24, or 213 days; in a closet from December 18 

 until July 24, or 22D days. 



Bacillus coli co7)imH)iis. — Lived in a vacuum from November 29 until 

 May 30, or 183 days; in a desiccator over sulphuric acid from January 

 3 until July 24, or 213 days; in a closet from December 30 until May 30, 

 or 152 days. 



Staphylococcus aureus. — Lived in a vacuum from ISTovember 29 until 

 July 24, or 207 days; in a desiccator over sulphuric acid from October 

 25 until April 19, or 178 days; in a closet from February 13 until 

 July 24, or 102 days. 



It will be seen from these experiments that the organisms experi- 

 mented on endure desiccation for live months, or more, without losing 

 their vitality, and hence the slight evaporation which may have 

 occurred in the insolation exjDeriments had probably no influence on 

 the results. 



It is evident that sunshine must exercise considerable influence in 

 destroying bacteria on the surface of soil, streets, etc., exposed to its 

 influence, but its action is almost contined to the surface, as a[>pears 

 from the results obtained by Esmarch in attempts to disinfect bedding 

 and clothing by this agency. While the light from an incandescent 

 electric lamp has little germicidal effect, that from a powerful arc lamp 

 produces effects similar to those of sunlight, and it has been proposed 

 to use this means to disinfect the walls of infected rooms. The bacillus 

 of tuberculosis appears to be more quickly destroyed by light than the 

 typhoid or the colon bacillus, being killed by exposure to simple difliised 

 daylight in about a week,' and this ftict should be borne in mind in 

 advising measures to x)revent the diffusion of this organism. 



The investigations upon the typhoid and the colon bacilli referred 

 to in this paper were undertaken as part of a general scheme of inquiry 

 to ascertain the agencies which tend to destroy the typhoid bacillus 

 when it is introduced into a source of water supply, as, for example, 

 into a running stream. An imi)ortant part of this investigation relates 



' Ueber l)aeteriolo<Tische Forscliuug : Vortrag in der ersten allgem. Sitzung des X. 

 iutcrnatioualen Congress, 1890. 



