196 APPLIED BACTERIOLOGY 



difference. Without assuming that these results would be 

 quantitatively true of all specimens of the diphtheria 

 organism— an assumption which is carefully to be avoided 

 in all inferences from bacteriological experiment— it is clear 

 from these results that even after an amount of desiccation 

 permitting the organisms to be freely carried by the atmo- 

 sphere, dust may contain living and virulent diphtheria 

 bacilli, and the air must be regarded as a powerful means 

 of spreading the disease. 



Several researches have demonstrated the fact that the 

 diphtheria organism may be capable of growing in water. 

 The experiments of D^m^triades (Archives de MMecine 

 Experimentale, 1895) are the best evidence of this capacity 

 in the diphtheria bacillus. He inoculated it in sterilised 

 distilled water, and found that it began to diminish only on 

 the seventh day, and did not disappear until the twenty- 

 eighth day. In such results the question always rises 

 whether the water was not rendered more favourable to 

 the growth of the organism by the accidental introduction 

 or inoculation of minute quantities of the nutrient matter 

 on which the organisms had been cultivated. 



With sterilised spring water the diminution of the bacillus 

 did not occur until the nineteenth day, and it survived till 

 the thirty-first. With various unsterilised spring waters the 

 organism survived and multiplied still longer for times and 

 to extents which appeared to vary with the impurity of the 

 water, and in particular with the amount of dissolved 

 organic matters which it contained. It is thus evident 

 that the diphtheria bacillus has a capacity of growth in 

 distilled water, and that in unsterilised natural waters its 

 vitality in the presence of other micro-organisms is entirely 

 exceptional in a non-aquatic microbe. Taken as a whole, 

 the experiments show that the bacillus may survive for 

 some weeks in spring waters of little organic impurity, 



