484 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



plates. Of seven tabes of agar-agar insolated forty days and then inoculated with the bacillus 

 of typhoid, all remained sterile. On four of these plates molds appeared after some days. Of 

 seven tubes of agar-agar insolated forty days and then inoculated and incubated as before, all 

 remained sterile. 



Insolated (lelatin. — Of ten gelatin tubes insolated forty days and then inoculated with the 

 bacillus tfiphi t(bd(niiiiKilis, six remained sterile, two contained a few colonies of hacillus fi/phi 

 abdominalis, and two were contaminated. 



It will be seen from these experiments that the long continued exijosure to sunlight of culture 

 media makes them incapable of supporting the growth of the bacillus of typhoid and of the colon 

 bacillus. 



II. DESICCATION. 



Bouillon cultures of the bacillus typhi abdominalis, the bacillus coli communis, and the 

 staphylococcus pyofjenes aureus were roughly dried ou threads 1 cm. long and then desiccated, a 

 portion being placed 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 diB'erent 

 conditions is as follows : 



Bacillus tjiphi ahdominalis : 



Lived in a vacuum from December liO uutil July 21, or 207 days. 



Lived in a desiccator over sulphuric acid from .lanuary 3 until July 24, or 203 days. 



Lived in a closet from December 18 until July 21, or 219 days. 

 Bacillus coli communis : 



Lived iu a vacuum from November 29 to May 30, or 183 days. 



Lived in a desiccator over sulphuric acid from January 3 until July 24, or 203 days. 



Lived in a closet from December 30 until May 30, or 152 days. 

 Staph ijlococcns pyogenes aiireus : 



Lived iu a vacuum from November 2!) uutil July 24, or 238 days. 



Lived iu a desiccator over sulphuric acid from October 25 until April 19, or 177 days. 



Lived in a closet from Febi-uary 13 until July 24, or 162 days. 



In will be seen from these experiments that the organisms experimented on endure desiccation 

 for five months or more without losing their vitality, and hence that what little desiccation may 

 have occurred in the insolation experiments had probably no influence ou the results. 



