Variations in Bacteria Caused by Change of Medium 



the collected organism in weighing bottles at 97 C. over calcium 

 chloride to constant weight, which required seven days, and cooling the 

 dried material in vacuo over the same dryer. Experiments in this 

 direction indicate that what holds true for bacterial derived sub- 

 stances (Leach, Journal of Biological Chemistry, 1906, I, 463), also 

 holds true for the whole bacterium, e. g., that bacteria show a great 



TABLE I 



avidity for water. The water content of bacteria, therefore, seems 

 to be subject to variations dependent on the time extent of incubation. 

 The variation does not seem to depend on mere mechanical adhesion, 

 because: (i) of the difficulty attendant on desiccation; (2) of the power 

 of absorbing moisture which dried bacteria or bacterial substances 

 display to such an extent that three days' exposure to ordinarily dry 

 atmosphere increases the weight of the desiccated material 0.05 per 

 cent. 



It may not be contended that the entire loss of weight by desic- 

 cation is due to water alone, since bacteria may contain volatile 



